Dave Grohl was just a drummer in Nirvana and most casual people/fans didn't probably know his name at the time unlike Axl Rose. But Dave managed to create Foo Fighters. Reinventing the wheel from scratch without looking back at his Nirvana years. Today Foo Fighters is headlining festivals.
If Axl would go completely solo,
under his own name or any other name than GNR,
and most importantly would behave like an organized, normal and active musician and tour, promote and release albums every few years,
His band could become as big as classic GN'R.
And to be fair