[Sergeytov]

A persistent world by most definitions can not be beaten, since the basic idea is that it exists perpetually.

I'm kind of meh on the four ages thing, mostly as someone who generally wants to think the places he plays on operate on a going concern premise. (That is to say, the game is not 'ending.')

Maybe I'm interpreting the question differently, but I don't know if what you are going after are 'ages' where everything changed a ton while people were out so much as the possibility for technology to advance with time. Depending on the code and such involved, I think this could be done with only a few troubles.
Maybe 'tech points' or something could be accumulated and spent on attempts to allocate them to certain fields, and when a field gets so many tech points new stuff starts coming out. Or you could preset what happens at tech levels in advance and have the stuff ready to roll out once that tech level is hit, depends on the nature of your game.

Maybe I'm kind of selfish, but now that I wrote this I'm thinking, "Man, this idea'd be cool to put in the game I'm doing development work on now."