As described here (http://bloody-disgusting.com/villainsmash/2015/08/06/the-x-men-are-finally-coming-to-live-action-television) Fox is looking into a live TV show that directly ties in to their established X-Men universe. But they're being hush on exactly what that will entail. So let's see what options there are...
We can rule out the X-Men proper, James McAvoy, Michael Fassbender, Ian McKellen, or Hugh Jackman aren't likely to move to the small screen any time soon. Patrick Stewart has done television before, but I believe he has a series coming out on HBO or Showtime, so committing to another full-time series seems highly unlikely.
Now one or more of them may be willing to do guest appearances, which is something Fox would have over the ABC & Netflix Marvel shows who lack any "headliner" cameos save for Sam Jackson's Nick Fury. Taking that all into account, the article's point of an X-Force show sounds like a very viable option. They'd just need to pick a bigger name for Cable, someone that can be the center of the show and make regular appearances in future movies (especially any more Deadpool features).
The other route they can go is by re-exploring Generation X. They tried it once before, and made a TV movie that, while kind of cheesey, wasn't that bad. The biggest issue they'll have with any show is budget. Most mutant powers require a high amount of special effects that most studios aren't willing to shell out for weekly unless it's a huge ratings draw. That's what killed the live action version of The Tick, which saw only a few weeks run on Fox a little over a decade ago.
They could also do a show on the Morlocks, sewer dwelling mutant rejects that are more disfigured than powerful. This could be their answer to the "street level" heroes Marvel does on Netflix. People ashamed of being a mutant just trying to survive in a world that hates them.
My wish would be that Fox realizes their latest Fantastic Four movie is a dud, and reboot it through TV. The Thing and Human Torch would require a lot of makeup and CGI work, but you can make it a science based family dramedy that might work better on the small screen.
Only time will tell what they end up doing...