Marvel’s been moving mostly to different descriptive names rather than different names within families for a while now. Avengers. New Avengers. Uncanny Avengers. All-New All-Different Avengers. Inhumans have Uncanny and Al-New. Same goes for X-Men. Prior to Secret Wars we had Amazing, Uncanny, All-New, “Wolverine and the” (and later “Spider-Man and the”) and adjectiveless “X-Men”. X-Factor was cancelled prior to Secret Wars so I’m guessing it wasn’t selling well enough. Now we have Extraordinary, All-New and Uncanny these days. With Magento’s “Uncanny” team being the deadly, hard hitting team with some former criminal mutants, it’s as close to an “X-Force” book as we’re likely to see for a while. I’m only speculating, but I’d guess that books with different adjectives - Uncanny and All-New, for example - that are both “X-Men” titles, are getting bought in greater numbers, just in case something happens in one that will affect the other. (I was buying Avengers and New Avengers for exactly that reason)

Books like X-Factor and X-Force are, understandably, their own things, rarely affecting the other titles (except when their own story gets put on hold for events). I’d say they just don’t sell, and I can totally see why Marvel would move away from such a concept.

It’s like solo X-Men series. They just don’t sell. Storm, Cyclops, and Gambit all had solo series end recently with no relaunch imminent. Wolverine is the only exception, obviously since he has “Old Man Logan” now AND X-23 gets her new solo series using his name, so “Wolverine” is still getting a solo book.