Here's my thoughts
I would love for the SA-MP server to still be going. It was nowhere near as customisable as GTA V (i.e. the best customisation you could get was skin mods...) but I spent upwards of 10 years on it, it worked, and it was enjoyable. I find GTA V's controls are too clunky compared to the more arcade feeling of GTA:SA.
That being said, there are too many limitations to just re-open the SA-MP server. There'd be very little development for many reasons, such as:
The language it uses, Pawn, is not used anywhere in mainstream development spaces and a lot of us have fallen out of touch with its syntax
It contains work created by other authors that are no longer members of this community - I would not be able to access the gamemode script because of this other work that cannot be shared without their consent, so on SA-MP I was restricted to creating scripts that could be copy and pasted into the gamemode when it was convenient
Many left SA-MP for GTA V, I am not so certain that these people would return to SA-MP if they're comfortable with GTA V
Most legal and illegal factions, companies, staff procedures and media is set up for GTA V. It'd be a huge task to move everything back to SA-MP, a lot of people would not follow, increasing the strain on other members of the community to pick up where others have dropped out
Now that SA-MP is gone, it needs to stay gone. Bringing it back for nostalgia would see limited success
As said in Martin's post, we are not aiming to be a competitor and never were, we aimed to release a barebones script, a minimum viable product, that the community could contribute to and build together. We are not expecting to dominate the GTA V roleplay scene (yet) as we are still building, learning from what the community wants. Our goal and objective is to make a server that players can be a part of when they want a good roleplay experience on GTA V.