That's a good point. I don't know if we have heard anything about those games being available day and date, which could certainly mean a delayed availability until PSX or something.
I do find it odd how these games were announced, given that it could indicate either full PS2 support, PS2 classics only support, or even just these games requiring new separate purchases. It is really only this thread and the PEGI leak about Dark Cloud, Ape Escape, and Twisted Metal that make me think this could be something good.
The possibility that this is just a big "fuck you, rebuy the games" announcement is certainly daunting even if I tend to think that is unlikely.
I really don't think we'll be paying to upgrade existing digital classics ala Wii to Wii U. I think a strong precedence exists which suggests against this approach.
They've been big on cross-buy for a while now, I have a number of digital PS3 games that have been upgraded and are playable for free on PS4 and in some cases a considerable amount of effort has been taken on porting the game. They could easily have charged for these but didn't.
Looking specifically at classics; If I recall digital classics originally launched on the PSP and then when the PS3 came around they were available on that for no additional charge. The same applies to the Vita (aside from the unexplained issue of some games never being made available).
The interesting question is will the full catalogue of digital titles be made available and how quickly will this happen. Hopeful of disc compatibility if only to allow us to play some of those games that will never be re-released digitally.
Obviously disk based emulation would be ideal, but if they do simply start selling PSX/2 games on PSN, they MUST launch it with a big selection and not drip feed them over the next five years. And they need to get their act together bringing games available in Japan/USA over to Europe. The localisation was already done first time around!