I know that remakes and remasters are contentious, but let's pretend whatever game in question you're thinking of is handled with the utmost care by your favourite devs and they absolutely nail it.
Mine would be Shadow of Memories (called Shadow of Destiny in North America). It's legitimately one of my favourite games of all time but it kinda flew under the radar and I haven't met many people who know of it let alone played it. Seeing it get modern graphics, maybe some expanded mechanics, would be soooo cool.
It's one of the coolest concepts I've seen for PSx. It's a rhythm game that loads into the console's ram, allowing you to swap the disc to one of your CDs and could generate unique levels for your songs.
While looking it up I did find there was a PS3 port, but I don't know how good that is or if it has the same custom level feature or not. I'd love a modern version that looks visually similar but allows you to either input a playlist from a service like yt or use your own local files to generate unique levels.
From what I've seen, it looks good. Can't play the demo for the 2nd game, but from some of the footage I've seen, it looks fun. Thanks for the suggestion.