emulators?

Alright, briefly, back on topic: what of the subject of emulating old-school arcade games? Those things have been disappearing from arcades and into storage or collector's hands for a while now I assume. I doubt anyone wants to hunt down the machines and spend their rent (and then some) for one machine. Well, they might if they really like the game and really like the arcade experience, but if they wanted more games...
 
can't you just switch out the carts of the old game machines and put in a different one. didn't they do that back in the day when a new game would come to the arcade, like playing street fighter alpha in an old street fighter 2 turbo machine.

I'd pay for a virtua on arcade machine