Floyd Mayweather tells TMZ Sports ... Logan's little bro is "probably" his next opponent, after he takes on Logan on Sunday.

... and why?? MONEY! MONEY! MONEY!

Check this out ... 44-year-old Floyd says he expects to make between $50 and $100 MILLION for the 8 round exhibition against Logan and believes he can pull similar figures against Jake.

In fact, Floyd tells us he's already raked in somewhere around $30 million for the Logan fight -- and that's in guaranteed cash before he even throws a punch.

Depending on the PPV numbers, Floyd says he can hit the 9-figure mark.

Floyd bragged that he changed the game with the first boxing/MMA crossover when he pulled $350 MILLION for the 2017 fight against Conor McGregor.

Regarding Logan, Floyd says he's aware people think it's a no-win situation for him ... but he doesn't care.

"To me, it's a win-win but I'm in a no-win because if I knock him out fast in the 1st round, they're gonna be like 'Aw man this wasn't worth it.' If I let it go a few rounds and drag it out, they're gonna be like 'Aw man, he let a YouTuber hang in it for a few rounds'. But, it is what it is. We're gonna have some fun Sunday."

As for Floyd's future, Mayweather says nothing is set in stone -- but "After Logan, probably Jake. We don't know. We will see."

Floyd and Jake definitely don't like each other -- remember, Jake stole Floyd's hat at a media event in May ... and Floyd was so pissed, he threatened to kill the 24-year-old.

But, before that can happen, Jake is set to fight ex-UFC champ Tyron Woodley ... someone Floyd wants to sign to a boxing contract.

"I would love Tyron Woodley to come to Mayweather Promotions, well Mayweather Boxing gym -- and I would love to sign Tyron Woodley so he can be fighting other fighters in the sport of boxing."

"Not on a high, high level but on the same level as what Jake Paul is doing because Jake Paul is fighting a bunch of nobodies. So, why can't Tyron Woodley do that and I sign him?!"

Floyd also says he wants to help train Tyron for the Jake fight.