Foo Fighters wouldn't be half as popular as it is since being the "drummer of Nirvana" is not important in this timeline. I see Kurt being like an Axl Rose in the present; outworn, just like Family Guy portrayed him, but sill not half as popular, maybe he would have a cult fanbase. And if he still didn't divorced Love, she would have dumped him for Billy Corgan and the Pumpkins would be seen as the "sucessors of Nirvana".