In a news story by C&VG they state that Free Radical are working on a third-person action stealth game for all the next-gen consoles.

One of their sources stated "It's a third-person action title with a bit of stealth in there - it'll be a huge departure from TimeSplitters but is shaping up to be amazing." so this new game may not be another TimeSplitters game but it looks as if it will be similar.

Eidos who handled the two TimeSplitters games are not handling this one, and it is believed that a major publisher will be handling it. More details will be announced at E3.