Parts of it will probably involve stealth, but the FAQ mentions that parts of it will have your character out in the middle of battlefields calling in tank strikes, battlecruiser strikes, and even nuclear strikes in order to help your side win. So it'll be a mix of both.
Personally, I'm surprised that it won't be available on the PC. The PC has been their main release platform for the last several years, and if they're making an X-Box version (which I imagine they are - they don't specify which consoles the game is going to be on, but it sounds like more than two) they'd already have half the work done for a PC release.
*grumble*
Of course, I'd also rather see an FPS version - perhaps something that was a cross between the game options of C&C Renegade (build a Starcraft base in MP mode? *grin*), the mission style of Deus Ex (multiple ways to finish missions, including stealth), and the Starcraft background.
Oh, well.