Garry's Mod didn't get replaced. It's still alive and well. The new generation grew straight into it and now are slowly moving to s&box (i.e. gmod2). It's just

Garry's Mod didn't get replaced. It's still alive and well. The new generation grew straight into it and now are slowly moving to s&box (i.e. gmod2). It's just as lively as ever but other games have blown up by an order of magnitude larger. Minecraft and gmod are still definitely staples of the young internet.