Boxing will find new stars easily enough. Guys that win in entertaining fights suddenly get more coverage, people get to know them and that's it. If they're on Showtime and they're good they'll end up moving to HBO. Like the Super Six winner will almost certainly be fighting Bute (provided he keeps winning) on HBO the first fight after he wins. If there looks to be a dearth of PPV potential fighters out there HBO will pick a deep division and match four top fighters against each other.

You may get one or two years when there's a bit of a lull but nothing to worry about long term. MMA or UFC or whatever will do its own thing, people will always be watching boxing.