While Jim Parsons would love Michael Keaton to join The Big Bang Theory universe, he isn’t holding out hope it’ll happen any time soon.

When Parsons appeared on The Tonight Show Starring Jimmy Fallon on Monday, April 8, the actor, 51, reacted to diehard fans casting the Batman star to take on a potential spinoff that tells the story of Parson’s iconic character Sheldon Cooper as an older man.

“It is interesting. There’s definitely a resemblance,” he marveled when host Jimmy Fallon held up a side by side photo of him, Keaton and Young Sheldon prequel star, Iain Armitage. “The one thing I will say is Michael Keaton — that really looks like Michael Keaton still, doesn’t it?”

Despite the resemblance, Parsons admitted that the possibility of a Keaton-led spinoff would be slim to none.

“Let me tell you this: I doubt that’s going to happen,” he shrugged. “But I would be so excited to have Michael Keaton added to the lineage of Sheldon portrayers. I would be amazed.”

He continued, “I’ve admired that man my entire life, starting with Mr. Mom. I mean, what a great guy. He’s a wonderful actor.” Parsons went on to reveal that he once met Keaton “in passing” at an industry event though they only exchanged a “quick hello and goodbye!”

With Young Sheldon well into its seventh and final season, Parsons and his former Big Bang Theory love interest, Mayim Bialik, will reprise their roles as Sheldon and Amy Farrah Fowler for its series finale on May 16.

Young Sheldon followed Cooper’s life as a 9-year-old child prodigy living with his family and attending high school in Texas. The series stars Armitage in the title role and also features Zoe Perry, Annie Potts, Montana Jordan, Raegan Revord and Lance Barber.

Though Parsons and Bialik’s cameo will be the first time any of the original cast members will physically appear in the prequel series, Parsons narrated the show for all seven seasons and Bialik has previously co-narrated as Amy in two episodes.

In November 2023, CBS announced that the hit spinoff would be concluding with its seventh and final season.

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“Being able to tell the origin of Sheldon Cooper, and expanding the story to include the entire Cooper family has been a wonderful experience,” executive producers Steve Holland, Steven Molaro and Chuck Lorre said in a joint statement to PEOPLE. “We are grateful to our fans for embracing this chapter of the Coopers these past six seasons, and on behalf of the entire Young Sheldon family, we’re excited to share this final season with you.”