The 49ers retain Hayne's contract rights after playing the ex-Parramatta, NSW and Australian rugby league ace - albeit fleetingly - during their last game of the season, a 19-16 overtime win over St Louis Rams, just two hours before Tomsula was fired.
The harsh reality, though, is the 49ers' new coach may well view Hayne's attempt at cracking the NFL big time a fanciful gamble and will have the option to cut him loose at any moment.
Even if the 49ers persist with their rookie recruit, Hayne still must endure the same painstaking and challenging process he did last year just to make the final 53-man roster from a 90-man squad for the 2016-17 season start in September.
But an upbeat Hayne is vowing to pursue his "dream" and says he already feels like a winner just by giving up his million-dollar-deal with the Eels to try to make it in the NFL.
"I chased a dream and I did that and everything else I achieved was a bonus. It's been incredible," he said. "All the support has probably been the biggest thing for me; all the support I received back here and definitely in California with the 49ers fans.
"To see so many Australians in the crowd. It was really good in that last game to hear the Aussie chant happening. That brought a smile."
After such an intense season, Hayne admitted he'd find it tough to zone out while enjoying family time in Australia.
"If anything, it's going to be the task to switch off," he said. "Obviously with the playoffs coming up, it's going to be fun watching that and I guess diagnosing their defence and offence. It's always fun.
"I'm still a student of the game, so there is always going to be a learning process that I enjoy."
Hayne described Tomsula as a huge influence in his maiden season and didn't know what his sacking meant for his own future.
"He was a massive reason why I signed at the Niners," Hayne said. "He did everything he could to give me game time and to put me out there, so I'm hugely thankful for Jim and everything he did for me."
-AAP