Third person CoD spinoff? It sounds weird because, like why? Don't get me wrong, it's a well known brand and I don't have a problem with the games, but it's just a weird IP (and really, it's a trademark at that) to have a spinoff for.
And I don't really have high hopes for Respawn. CoD was a game I had a ton of fun with at the time, CoD2 actually felt really really dated, but I was pleasantly surprised with CoD:MW. The thing is that a lot of the appeal of it was just the extremely high production value, great set pieces, and the modern environment. The following MW games followed it up very well, but again, it feels like the gameplay itself hasn't evolved and it's floating on the merits of the money thrown into it. I think the fact that the Black Ops games are equally well received kinda goes to show that Infinity Ward might get a little more credit than it's due.
Again, not that they don't do a good job, but as far as I know, the people behind Respawn have developed two games: World War 2 shooter and Modern Era shooter. They're good at that, but the actual gameplay mechanics are STILL dated (MW almost feels like an on-rails shooter) and I think they may have a problem transitioning into a new IP. Well, that, or it will end up being yet another modern FPS in an already saturated market. And we all know the MP won't touch BF3 anyways.