In fact, Capcom already has their own God of War... it's Asura's Wrath.
Except their quality is nothing alike at all. AW has one of the worst combat mechanics I've played in
any video game. God of War is far and above, superior in every way. Play the demo of AW, and you'll see how sloppy the combat is. The constant QTE sections are a little annoying, however I can't deny that it's satisfying.
Game controls from the God of Wars, I really like the straight forward free roaming play. Also, the quick weapon switching, would work good with the Legends 3 arsenal.
The puzzle and enemy fights, I can see that same kind of thing, for any ruins and/or the moon.
But, most important, the graphics. Primary reason why I want the G.O.W creators, to make the game.
I agree on the free roaming aspect, although I'd want L3 to be more environmentally interactive than GoW ever was (destructable buildings or objects) and scaling the walls like they've shown with the Prototype. Quick weapon switching is definitely a good idea, but the fighting in the Legends franchise should always stay ranged, not close combat (unless on occasion with Barrett's melee attacks).
Graphics are far from the "most important". Gameplay always comes first, control second, with graphics simply finishing up the presentation.