Just a thought. Since movies are open to a much wider audience than TV (or at least people follow movies more than they follow TV shows) and the 24 movie is a hit at the box office, do you think these new people introduced to the 24 universe will encourage the writing team and cast to produce a Season 9 as a proper end to the show?
Use Season 9 to tie up all the loose ends from Seasons 1-8. All the unanswered character arcs and storylines. Give a final ending to Jack's adventures. Movies make much more money then they cost to produce, especially with a real time format, so I think a Season 9 is not yet out of the picture completely.
Note: I've only seen Seasons 1-4 so no spoilers for 5-8 please.