The problem I see with any bill of rights as such is that to my lawyerly ear, any time someone mentions the word "right," then that places someone else under a duty. If you're not using the word "right" in a legal sense, but rather in the sense of what companies should do (as opposed to what they must legally do), then the bills of rights have no legal teeth and the companies may safely ignore them (even while paying lip service to them, no doubt.)
So, for instance (and to take an extreme example) if gamers have the legal right to play a game forever, then the game owner has the legal duty to make it available forever, and the owner simply isn't going to agree to have his hands tied like that. Since corporations are going to chafe at any such legal restrictions on their right to run the game how they want, subject only to what their business model says is good for the company, they're not going to be inclined to grant any rights that they find too restrictive. And if you could somehow force them to accept these rights, at some point at least some companies would decide developing a new game isn't worth the hassle.
I think that what we will actually see is an evolution of IP law that will recognize some legal IP rights in the players. If this develops gradually over time, and slowly becomes a legally-imposed industry standard, the corporations would probably accept it. Part of it would be market-driven; even if most corporations decided not to develop games because the new rules made such development too burdensome, the increased potential market share of potential gamers without games to play would entice other companies to publish games despite the new legal requirements.
I think that we'll eventually see this happen for a couple of reasons. First, EULAs are generally seen as adhesion contracts, which the law sort of dislikes anyway, especially when the terms they impose are inequitable. But more importantly, as just about everyone here can attest, we the players _have_ built a world within Paragon City, which includes characters that are at least somewhat individualized, AE story arcs, and personal relationships (i.e., it isn't NCSoft that's built the community and the friendships, but we the players). Some of this IP input, moreover, has been of extremely high quality, which might have an impact on valuation. (I always get envious whenever I read a character bio that is so much more imaginative and creative than anything I could come up with.) We've also done this not in minutes, hours, or days, but by putting in a great deal of time, hundreds or thousands of hours in the case of some people. I thus think that, ultimately, the Lockean theory of labor-based value and modern psychology and sociology are on our side.
One practical effect of time is that the youngish gamers of today, who really understand the community dynamic of gaming, are currently law students and young attorneys, but thirty years from now they'll be judges and legislators, and they'll shape the law according to their experience. I'm already reading some of the Young Turks' legal analysis, and if these people become judges and legislators--and some of them doubtless will--they're going to be very open to redefining MMO IP rights.
What will the new rights be? Will some of the rights listed in this thread be among them? Your guess is as good as mine, but some games may already be showing us the way. Second Life's EULA expressly recognizes that players have some IP rights. EVE Online has some sort of panel of players' representatives, formally recognized and listened to by the corporation, elected by the players. So I think that we do have some possibilities. But the process will be slow, and it's full of imponderables.