As someone who rarely watch the show "24" and didn't get a good impression of the show, i have strong inclination that the comeback show will be a flop. The show seems to last forever, and had the same plot in every episode which made me lose interest quick. From personal experience from watching the show "24" I really don't expect the show to gain any traction from viewers.
As of the typing of this message, we have very few details to make such a statement. Considering that this is only going to be about 12 one hour episodes, there is bound to be less filler to these episodes considering how much less time there is to go through the whole story.
The comeback is a single, 12-episode season (this will allow the writers to make a better story than the 24-hour seasons, and will remove a lot of the 'dead time' in the show). It is not only a test of 24's enduring popularity, but also a new concept of a limited return of popular series'. Fox cannot afford for it to fail, and it will not.
24 was one of the greatest shows of all time. With its original concept, star power, and all-around great action, people will be eager to see how it turns out. Even if it is only half the quality as before, it will be at least marginally successful. It will maintain a cult following, and will draw in in a whole new audience, who will then go back and watch the old series via streaming.