One of the advantages of free to play/microtransaction games is that they have a very low barrier to entry. You simply download them and start playing. If you like them, then you might "enhance" your play by purchasing items from a cash shop. It is because of this that many people insist that free to play with microtransactions is the future of MMORPGs.
I have to wonder if it's really the MICROTRANSACTION/Item Shop part that makes these kinds of games appealing? I really don't think so. I think the main attraction is that it's free to download and play the complete game, and IF you like it, you can choose to pay for additional features. If you play for months and then decide that the end game wasn't what you thought it would be, you aren't out any money, if you choose not to pay. That is a greatly appealing prospect.
This could be done in a subscription based game as well. A subscription game could offer the basic game for free and reserve some special features for subscribers. Aside from Anarchy Online, I'm not aware of any major MMO that does, and AO doesn't do it quite how I envision: they open up the original world only, but once you subscribe you can't fall back and become a basic, non-paying user. You also can't add on expansion packs without becoming a subscriber. So while the basic game is free, it ends up being more or less like a rather large "trial" area.
A better model would be to offer the entire game to users for free, and reserve a handful of FEATURES for subscribers. You could still have expansion packs but both free users and subscribers should be able to apply them to their accounts. And subscribers who decide to stop paying would be converted to free users when their subscriptions ended. This would make the game work much like most Internet services, such as Plaxo, and LinkedIn, etc. where the basic features of a complete, working service are all available for free and only a handful of features are reserved for subscribers.
Let's say EverQuest II adopted this business model. The freemium accounts might restrict you to one or two character slots. The characters would lose some of the perks normal characters enjoy, such as Vitality, and maybe they would gain combat XP (or convert combat XP to achievement XP) at half the normal rate. They wouldn't be able to access certain other features, like the recently announced Research Assistants. They would also be unable to /petition or use customer service, since a lot of our subscription fee goes towards funding that. And maybe there would be a limit to the amount of time the player can play the game per month using one of these accounts.
But other than that, they should be able to do and access everything in the game that normal subscribers can. They could level up to the level cap just like subscribers. They could access any zone that subscribers can (assuming they pass the same access restrictions that subscribers have). They could buy an expansion pack, just like subscribers do, and they would have the option to unlock the zones and new content without subscribing (possibly converting the unused free time into Station Cash.) That way they can still access newer content without being forced to commit to shelling out $15 a month.
You would have an influx of people who might not subscribe, and might never subscribe, but they would contribute to the life of the game, making it more enjoyable for subscribers. They would do this by creating a market for additional goods, acting as new players to group with, and breathing new life into the chat channels, cities, and public spaces. Because they would level up slower, they would reintroduce a level of relevance to the low level content that has been lost over time.
The main drawback to this idea would be with gold famers, since they would flock to a free account en masse. But here's an idea that might work: make it so free accounts can't access (note: the key word is access, not earn) more than 1 platinum a day (or some other arbitrary amount). While adventuring, at most 1 platinum (or a variable amount based on character level) goes into their inventory. Any amount that they earn from combat, quests, the broker, or through trade in excess of 1 platinum goes into an escrow account. Every day, at most 1 platinum in that escrow account will be transferred to that character's bank slot.
This means the free accounts can still do anything subscribers can but their ability to amass in game wealth is simply slowed down. This shouldn't negatively impact game play, because these accounts would mostly be used by casual players.
If the free accounts are time limited as well, that would be a further obstacle that would make them unattractive to gold farmers.
While a bunch of farmers can get free accounts and go out and earn 100 platinum, they would only end up with 1 platinum in each of their inventories. It would take 99 days for the rest of that money to trickle into their characters' bank account. That would severely slow down the potential of earning business on those accounts.
Another feature of freemium play that is important: users (players) need to be able to go back and forth between free and subsription accounts at will. Anarchy Online only lets you upconvert but once you start subscribing, you can't stop and still keep playing. You also can't upgrade your account to access any of the expansion packs without subscribing.
It would be better if you just convert accounts (in good standing) that stop paying to a free account; they would lose access to all but the one or two characters that the freemium accounts allow, and so on, but they could still log on and play. The reasoning here is that much of the value of a multiplayer game is the community. If someone no longer has the time to keep playing enough to warrant the subscription fee, having their account converted to a free account means they can still at least pop in once in a while and say "hi" to their guildmates, help out on a raid, and contribute to the life of the game, which makes the game more valuable to those of us who are still paying to play.
Let's take what works about the free to play/microtransaction games: the ability to drop in anytime without commitment, the ability to try the game without the hassle of finding a box on the shelf at Gamestop or pulling out a credit card, the ability to pop in and keep in touch with the friends you've made online even after you've "moved on" to greener MMO pastures. Take that, but apply it to the traditional subscription based business model, without forcing us to deal with all the game impacting microtransactions that almost all Free to Play games (like the current darling of the blogosphere, Runes of Magic) have.
I don't want to pay extra for bag slots (meaning the developers have an incentive to dump all kinds of junk in my bags). I don't want to pay real money to respec my character because the developers don't give me an in game option. I don't want to pay real life money to rent a stupid horse or use my recall spells.
I just want my traditional EverQuest/EQ2 style gameplay, but with an option for a limited (but not a trial) account that could help bring in new players AND bring back old players to breathe some life back into their aging games -- and make the subscription fees that the rest of us are paying more valuable.