Fox entertainment co-chairman Gary Newman is reportedly their source, saying that negotiations with Marvel, who have to sign off on the project, have slowed the process.
"It's in negotiations," Newman said. "We're cautiously optimistic, we had a good meeting with them. That will not be on a fast track creatively. This is just the deal, now we have to find the creative."
For that reason, they're focusing on the contracts rather than the concept and so there isn't yet a creative team or even a specific idea behind it, although TV Insider says there's rumors of an X-Factor adaptation.
Back around the time Marvel's Agents of S.H.I.E.L.D. was in development, Cougar Town and Enlisted showrunner Kevin Biegel had said on Twitter that he would love to develop a series based on Madrox, the Marvel miniseries that kicked off an X-Factor relaunch.
"Someone call Netflix right now and tell them we'll do that show as a Simon and Simon / Magnum PI-style hour long fun procedural," he said during an interview with ComicBook.com last year. "I mean, they'd hang up on us...but come on!"
Because of the negotiations and development time required, Newman told TV Insider he doesn't think a show would be ready before the 2016-2017 TV season.
With Marvel and DC properties making the move to TV all the time, it's perhaps surprising that a network that skews as young as FOX does only has Gotham, with a police procedural feel that seems a little more CBS than their average series.
The fact that their parent company, 20th Century Fox, controls the X-Men rights, hasn't escaped anyone's notice, though, and there's been talk of something like this for months.