That shouldn't be much of an issue in regards to downloadable games. Games like Braid and Limbo are on the PS3 and 360, plus the PC -- that game isn't using anything hardware specific. Sony, at least, has some precedent for 'transfer' -- any PSP games you downloaded will transfer over to the Vita; PS1 games only had to be bought once, and they could be played on the PS3 or PSP, and ultimately Vita. PSN and XBL won't 'start over' when new consoles come out, they'll still have the majority of that content available on day 1, because that's the appeal of digital distribution.
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"When I was a young man, I had liberty, but I did not see it. I had time, but I did not know it."