How The Big Bang Theory Star Jim Parsons Feels About Michael Keaton As Sheldon Cooper

"The Big Bang Theory" was never a critics' darling, to the extent that reviewers were a bit stunned when they found themselves gradually won over by "Young Sheldon," but both series were massive Nielsen ratings hits that managed to attract loads of big-name guest stars. The former earned its nerd bona fides by landing appearances from "Star Trek" legends like Leonard Nimoy and LeVar Burton, while touching television immortality by casting sitcom god Bob Newhart as Professor Proton. As for "Young Sheldon," the producers happily welcomed Newhart back as the TV science host, and also brought on notable talents like Melanie Lynskey, Jason Alexander, and Lance Reddick.

So no matter how you feel about these ultra-mainstream shows, you've got to accept that there is no shame in playing the cameo game within "The Big Bang Theory" universe.

Now that we know CBS will be delving further into this geek-pandering realm with "Georgie & Mandy's First Marriage," a sequel to "Young Sheldon," you may find yourself asking the question, "Could a 'Big Bang Theory' spin-off ever cast an A-list actor in its main cast?" Granted, you'd have to be awfully bored and/or obsessed with these shows to ask this question — or, worse, you might be Jimmy Fallon.

Oops, I forgot to properly finish that sentence. Let's try that again.

You might be Jimmy Fallon interviewing Jim Parsons on "The Tonight Show," and noting that a photo of a young Michael Keaton that got to floating around the internet for whatever reason bore a strong resemblance to Iain Armitage, who played young Sheldon Lee Cooper for seven seasons. And if you're Parsons, you'd be forced to answer the question, because that's how talk shows and interviews in general work.

What would Parsons say in such a situation? The world received an answer to that question when Parsons dropped by "The Tonight Show" earlier this year.

After acknowledging the resemblance between Young Sheldon and Young Keaton, Parsons answered the question on Fallon's mind: Could "Old Sheldon" starring Michael Keaton be in the offing? Parsons was quick to respond: "Let me tell you this: I doubt that's going to happen."

As for whether Parsons thinks Keaton could handle the rigorous task of playing an aged iteration of the smarty pants character, the sitcom star was shockingly complimentary of the legendary, Academy Award-nominated actor. As he told Fallon:

"I would be so excited to have Michael Keaton added to the lineage of Sheldon portrayers. I would be amazed. I've admired that man my entire life, starting with 'Mr. Mom.' I mean, what a great guy. He's a wonderful actor."

"Mr. Mom," eh? I will not stand for this "Night Shift" erasure, especially from an actor who's my age, and was therefore old enough to sneak a viewing of the Ron Howard-directed R-rated comedy when it aired incessantly on pay cable throughout 1983. Perhaps he wasn't that savvy. Or maybe he just hates Shelley Long.

In any event, you can expect "Old Sheldon" starring Michael Keaton to never happen, while Jimmy Fallon will continue to justify his existence for the foreseeable figure by giving The Roots a network showcase five nights a week.