I agree with Nitwick. Minecraft is gonna be here for a while. And the server you create will determine its popularity. If it's unique, fun, and an overall great community you should have no problem with it becoming popular and well-known. Plus, I feel like GMOD has a ton of darkrp servers already, but the possibilities of creating a unique server is vast.

If you base your assumption on the number of servers released on a daily basis, minecraft is most certainly not dying. Have no fear of that.