>>149381134 (OP)Just Hillenburg? I think Season 4 would've ended up being pretty good, but probably still a step down from 1-3. Like others have mentioned, a lot of Season 4 episodes were ideas the team came up with before the movie, so there were some really good concepts in there. I bet having Hillenberg around would've made a big difference. After that, I still think you'd see a decline. These shows are a team effort.
If everyone stuck around, I'm gonna say it would've been good for 5-6 seasons. That's just sort of a guess though. There's no way it'd have stayed good for however the fuck many seasons it has out now.