Ah, thats right. I forgot about that.
I know there's at least one fanfic kicking around (quite a good one as I recall) dealing with Hopper's return.
As far as Kermit interfering with Hopper's continuing success despite him, well, just picture the following cozy family scene.
------------------------------------------------
Dad: Well kids, what would you like to do? Sit down and watch The Muppet Show with Kermit the Frog or go out to eat frog leg's at... at.... what's that place called?
Mom: Oh, you mean the place that has that old guy in the hideous frog costume dancing in a highly disturbing way? Doc Hopper's, I believe.
Dad: Oh, that's right. What do you think, kids?
Kids: Muppet Show! Muppet Show!
Mom: Sounds good to me! I'll just turn on the TV... oh, look, it's that Doc Hopper commercial again.
Innocent, trusting children : AAAAAAIIIIIIEEEEEEEEE!!!!!!!!!!!
--------------------
Need I say more?