The normal untouched (without it being hacked/tampered with) game can only handle 110 vehicles loaded at one time, and around 120ish Actor/players at any one point in time...
If you try to force the game to spawn more than these amounts the game simplally crashes because the pool size gets too large and overwrites values that are needed for the game to operate properly. (or summit like that)
Custom tracks would probs be a big no no...
this is cause the train track is a set of node points, that are defined via a file - Prehaps you can make a resource of new node points, but its not easy and may never be supported by MTA.
People still play C&C Generals you know, and they even still play C&C1... even know C&C 3 is out, they still play it...
Just because GTAIV is comming out, does not mean GTA:SA will automatically die...
The Trailer sucked tbh - Sure amazing gfx, but didnt show enough!
Here is a nice fast download URL for you: http://srv1.alienxsoftware.co.uk/gtaiv/ ... 1_720p.wmv