The big money boxing bout was confirmed in June and will take place on 26 August as McGregor will put his UFC career on hold for what is being billed as "The Money Fight".
However, with both fighters expected to earn in excess of $100m (£78m), many in the combat world believe that the lightweight champion will retire from the UFC shortly after as there is no chance of him making even close to that amount again.
But Kavanagh claims that money alone will not stop McGregor from competing in the octagon as he is still very interested in challenging himself.
"I don't see any reason why he would not [return to the UFC]" the Straight Blast Gym coach said, as quoted on MMAFighting. "Certainly money would not be the reason why he would not do MMA again."
"He has said very clearly to me, 'Get ready, we're back in the cage in December.' I hope someone out there has sparked the interest in him to make him excited about that."
That someone might be lightweight contender and undefeated Khabib Nurmagomedov, who UFC president Dana White recently claimed was on McGregor's fighting wishlist.
If the "Notorious" does end up defending his lightweight title after the Mayweather fight, he would be proving many people wrong who claim he is only in the game for money.
"It's not money that's motivating him anymore," Kavanagh added. "He could very easily make similar money from doing some movies or doing endorsements."
"It's the challenge. That's why he's in the gym laughing every day. If he left the gym now and stopped fighting, what would he do with his free time? You can only sit in one car at a time, you can only have one meal at a time. Eventually you want to do something that's enjoyable to you. And that would be Conor drifting back into the gym. It's what's enjoyable to him."
Kavanagh is not the first to claim that the 28-year-old will continue fighting in the UFC. His teammate Dillon Danis also stated that MMA was McGregor's passion and predicted his return to the octagon.