I wouldn't be so sure on any DLC yet. Well, for the Wii U version at least.
That's actually a very good point.
It helps that the developers have been around the block quite a lot. Despite what others think, they also listen to the community.
Over the years they've been able to perfect the core set of gameplay mechanics. It allows them to focus on other areas add/improve/remove etc.
Even in my case, where I haven't played COD in a few years (WAW-MW3 for the Wii. MW-Black Ops for the home consoles) I was still able to get back into it within a few gaming sessions. Things like the HUD & controls have been consistent through the years which helps too.
A lot of people tend to throw insults towards COD very easily, but they overlook some of the good things too.