What do you mean 'worse,' exactly? BCR on the PS3 and 360 are pretty much the same. MM9/10, too. BCR2 has the 'must be online' DRM on the PS3, but otherwise they should play the same. I can't say I know the details of what the coding involved with these digital games is, but I do know they're not nearly as tied to the console hardware as, say, Uncharted might be. It's hard for me to see a situation where the hardware next-gen has a hard time playing these downloadable games coming out right now, and that they would need to be redone to work and play properly.
I think the content on PSN and XBL would be a priority for Sony and Microsoft going forward, and they would make sure people going to the PS4 or Xbox 720 could expect not only that their previously bought games will still work but also that there will be a full store of games ready to purchase. It's an easier bet to make than actual PS3/360 BC, I would say.
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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."