Not if I have the originals. I hate buying the same game, just "HDer". It just doesn't seem worth paying full price for again.
If I got a PS4 and didn't have The Last of Us on PS3, I'd totally get that version! But I do have it on PS3, and it is a remaster featuring improved… framerate and resolution? I don't think that's worth a re-buy.
MGSV on the other hand… well it isn't out yet, and is being developed for all platforms AT THE SAME TIME. Which is the key, because then the core game is built to run on all systems properly from square 1, and then they just get the better hardware and expand on this stuff. So seeing as how I know I'll be getting the PS4, I'll wait for the PS4 version for that game, and get the better resolution, framerate and object quality. The same is to be said about LBP3, except I expect a lot less of a difference between PS3 and PS4 for that game (from what I've seen in the beta).
MGS3 is the best example of a Classics HD that really was genuinely special. Because the original PS2 MGS3 was of a top-down view and had awkward controls (among many other things). They eventually decided to try and fix this with a PS2 re-release called subsistance, but I don't believe many people were all that keen of re-buying it. Subsistance also had heaps of cool goodies such as re-masters of the MSX games (quite good remasters, in that the translations and character images were fixed to be more representative of the characters as they appear in later games). Then all of this was released in the collection for PS3 with MGS:PW which was previously only available in low res for PSP.
Best. Collection. Ever… I should probably buy it for PS3 sometime, to play MGS:PW co-p just to honour it's awesomeness.