There's no way that they're going to go back to Marathon after being trapped in FPS purgatory for a decade. They want to stretch out and try something that's actually different, if not something truly new. They'll probably get back to FPS after they've put out a couple non-FPS titles.
I'd love for them to return to Oni, simply because I felt that it was a good concept with gameplay that worked quite well, but didn't quite realize itself in terms of level design or story. I'd like to see what Bungie might do with it now that they have all the resources of a giant developing house.
Edit @ Slimebeast
Marathon 2 was released on PC and has since been re-released on XBLA.
Of course, other people might be familiar with it from Aleph One, an open source port of all Marathon scenarios, plus tons of mods, running on the modern PC platform of your choice.
"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
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