Honestly, we don't have an accurate or even an estimated answer.
It all depends on SystemFiles' free time, which lately he barely got any..
I want to believe it will be on day one, but I'm not going to promise anything at this point.

As for beta.. That will depend on us obtaining a copy of the beta and again, SystemFiles' personal free time.

As for the game itself, I doubt we're talking about any colossal change, through up the years COD base engine haven't changed dramatically, it's always been a copy pasted with a few improvements here and there.
However, it's hard to talk about something that haven't been out yet. I could be very wrong on this one.