Will America still be interested if a superstar HW appear? Or it's now too late.

[FightersRep]

it's too late, boxing is doomed to fail with better avenues for athletic endeavors and mma

While I don't completely disagree with this, I don't think Boxing is or will ever be doomed. There have been past cycles where people thought boxing would disappear, only to have an exciting fighter reinvigorate the sport again.

[SoulByThePound]

An exciting heavyweight will garner attention anywhere.

David Haye could have been that HW if he travelled to the US and backed himself to beat their lot instead of staying inactive and only chasing huge paydays which probably won't come.

he's not american so no