Talk about a game changer: We’ve known for a long time that NBC would take Jay Leno off “The Tonight Show” this spring to turn the slot over to Conan O’Brien. So, where’s Leno going?

After lots of speculation, the answer is … NBC. Bill Carter says they’re going to move his show intact to the last hour of primetime, five nights a week. That means Leno will fill more hours of evening television than anyone since Regis Philbin hosted “Who Wants To Be A Millionaire?”

Will it work? Two guys whose opinions I respect on matters such as this — Mark Evanier and Aaron Barnhart — agree that it will. And they speculate on what it means for Conan, Jimmy Fallon, and Hollywood’s producers who will now have one less hour of primetime available to fill.

Mark says,

The move will piss a lot of people off, including producers who’d been hoping to sell new shows to NBC. Leno’s going to consume five hours that could have been available for their wares. And you have to wonder how Conan O’Brien’s viewing it since he’ll still be second-in-line for the big guests…and now that he’ll be in Hollywood also, that may make it very difficult. The folks behind Jimmy Fallon’s new program, which will take over Conan’s old time slot, have to be wondering if viewers will really want to watch three talk shows in a row.

Aaron’s take:

It gives the local affiliates a sure, stable lead-in to their late local news — you’ve got to think GM’s everywhere are popping corks after suffering through years of dismal lead-ins. Here in Kansas City KSHB suffered doubly in the November book because of appallingly low numbers from “My Own Worst Enemy” (aptly titled) and other lead-ins to late news. It took a hit in the evenings, and then took another hit in the mornings when people woke up and tuned into whatever network affiliate they were watching the night before.

It gets NBC out of the 22-hours-a-week prime time programming business, at which it was presently sucking, and into the 17-hours-a-week business, just like Fox.

And of course, it locks up Jay Leno and prevents him from going to ABC — where, frankly, he would not have done as well as he will here.

Best of all, this probably means some job security for my friend Jon Macks, who has been writing monologue jokes for Leno since his debut as host of “The Tonight Show” more than 16 years ago.