I wouldn't expect up-res/anti-aliasing/etc from their PS1/2 emulators on PS4. Higher res and AA cause a lot of weird issues on some games in emulation, and it's not always an imperfection in the emulator, some games just do weird crap that isn't visible at native res. It'd be cool if it were an option of course and it should be LESS buggy than fpse/PCSX2 and such but I'm not sure it'll happen. Would certainly be nice though.
Heck for now I'd be happy with just the PS1 emulator PS3/PSP/Vita have, it's clearly ready to port to different systems, PS2 will take longer but we should be able to get PS1 fairly quickly. I don't buy the PS Now excuse, they don't even have PS1 games on PS Now yet, and it's a massive waste of tech and bandwidth to stream <1GB games over a moderately high bitrate video stream. PS3 makes sense because PS3 emulation will take ages to be viable. Plus they already have digital distro licensing deals for a lot of these PS1 games.
Also, the single most important part of emulation on PS4 if/when it happens: cloudsaves for PS1 memory cards. The current situation is super annoying across PS3/PSP/PS Vita. Moving saves for more than a single game is an arduous task.