I agree with tippy, too. After Phantom Pain, Konami is likely pulling completely out of the major video game market, to focus on mobile games and slapping Snake and the Belmonts on the sides of pachinko machines. For the foreseeable future, I doubt they will bother with the effort to even port existing games over.
Square, on the other hand, has been remaking and porting their catalog over 4 generations of consoles. It's surprising that a KH collection and a FFXII remaster hasn't been announced yet, with all the fan demand I've seen lately. E3 might have some good news (if they don't pull that bait and switch with FF7 again and say it's coming to mobile or N3DS or toasters).
For PS1 and PS2 classics on PS4, I don't think it's happening. Sony wants to push that streaming service of theirs. They don't want customers paying a one time fee for a game when they can milk a steady rate out of their wallets. Maybe they'll change their minds if enough people complain that their internet connection isn't good enough for game streaming, but we haven't heard anything from Sony about downloading any full games from the previous generations. Until we hear that you can at least transfer your existing collection of classics over to a PS4, I'd say anyone attached to what they've bought on the PSN should keep their PS3s. I'm not giving mine up.