(EA had two fun little browser-based Command and Conquer games... one where you drove a tank around and one a helicopter... and one day they just took them down. Are those preserved somewhere? Not as far as I can tell.)
As a game developer, I can sorta reassure you on that point, though it's not much of a reassurance. I am virtually certain that every single one of these projects is preserved in a more amazing way than you can imagine - thanks to modern versioning systems, you could not only recreate the final product, but also any intermediate stage along the way. The way versioning systems work is that all files are committed to a central server, which not only preserves the latest version of the file, but also every previous version along the way, together with information on when each new version is added and by what user. If you have access to the server, and a lot of time to waste, you can retrace the entire course of development, the successes, the failures (where bad code needed to be removed, by reverting the file to an earlier version), everything. And generally, game developers these days are far more careful about preserving data than in the 1990s, simply because it's just so incredibly cheap to do it these days.
So much for the reassurance part, now for the less reassuring part: nobody cares. I mean the people working there. Nobody cares about preserving anything. Everyone commits everything to the server, the server is regularly backed up, so in theory everything is there... but in practice, these backups serve purely a technical function: they're not there to preserve things for posterity, but merely... you know, as backups in case of some equipment failure. What this means is that nobody really cares what happens to the backups after they've served their function - a backup more than two weeks old is useless. It's not thrown out, it's not overwritten, it's just... forgotten, dumped in some storage room only to eventually be thrown away when physical space starts running short. And of course, nothing can be simply thrown out or given away (though fortunately, people break these rules all the time, and nobody really cares), because corporations are also more careful about NDAs.
The only pieces of data that are preserved more meticulously are the gold masters - and as you can imagine, that's not a concept that applies to social games. That said, I'm sure that proud developers retain copies of their social games at various stages - I bet that original FarmVille is somewhere out there.
(that said, it's FarmVille, not Shakespeare... we really shouldn't care that much
; studying the hugely influential concept of social games doesn't really require us to see a specific example)