I personally don't see any sense in setting up a multiplayer modification for GTA SA Remastered.
SAMP, or GTA SA is what is it. I love it's broken physics, it's shitty graphics, especially it's low system requirements.
There are many reasons why people love to play this game, even if it's old. So for sure GTA SA will have a multiplayer modification one day, but it's a different thing, and should not be related to SAMP in any way.