User blog comment:JoshCF1/The State of the Call of Duty series./@comment-1646923-20110206171106/@comment-1191892-20110206210606

I believe the main thing that matters with slogans is if they're trademarked, not copyrighted (slogans can't be copyrighted, in fact). For example, Nike's "Just Do It" or McDonalds' "I'm Lovin' It." In this process whether you came first doesn't even matter; for example, Games Workshop owns a trademark on "Space Marine" and even though Aliens used the name first, Aliens has to acknowledge that GW owns the name on anything that uses it.

So it's entirely possible, if Bethesda doesn't have any kind of trademarking in place for "War never changes," that they could end up paying royalties to Activision. The most likely scenario would be "nothing happens."