Would be amazing, but very hard to code. And I havent seen it yet
I have seen a project about making oldschool maps HD but keeping everything else like 06-07 style, thats as close as I have ever seen it
It would be difficult making everything from scratch, however I'm just surprised nobody has tried making an original private server (out of like, the 2000 RSPSs that exist, lol).
I find the problem with these "nostalgia"/remake servers is that everything is predictable (don't get me wrong, I like playing 2006 remakes). It's impossible to relive the fun moments you had as a kid, because you're playing a remake: you already know where to go, how to play, what happens next, etc.
Hopefully someday a person will make a RSPS with unique maps and quests (or perhaps a game similar to Runescape, with just better improved graphics and gameplay).