Fallout 4 is going bring that to new heights too, I have no doubt. As if to be an indicator, the mod community is already working on content for the game and we are still four months out. On the Bethesda forums (via VG247), Modder Zealotlee claims that they are already working on content for the unreleased game. At the moment, the mod is currently just a Rail Rifle, but I have no doubt this community will get very elaborate, very quick.
I can't wait to see what modders do with this game. The new software, the new world, the new graphics…it is going to open up a lot of possibilities. I have no doubt we will see the player base of Fallout 4 last for years and years because of it too.