(Apologies for double-post.)
I e-mailed Karen Traviss, asking if the book was going to be tied-in with an Republic Commando sequel. Here's her response (she responded FAST).
Hi Joe. It's the sequel to Hard Contact, and it has all the Omega Squad characters plus Delta Squad and the Null ARCs that I introduced in Targets. It'll be published on February 28. It has nothing to do with any game.
Hope that helps.