I think IW failed because they did 3 futuristic games with jetpacks in a row (AW, BOPS3 and IW). People got a bit tired of that maybe (?). At least before they alternated:
COD4 -> present warfare
waw-> wwii
mw2 -> present warfare
bops -> vietnam
mw3 -> present warfare
But then they did:
AW -> futuristic bullshit and jetpacks
Bops 3 -> futuristic bullshit and jetpacks
IW -> futuristic bullshit and jetpacks
Black ops 3 sold a lot and that proved people liked the AW jetpacks and the black ops saga, but releasing a third game in a row with that kind of gameplay probably got people tired, they can just play bops 3 another year or even go back to bops 2 that is now backwards compatible and there's a lot of people playing on all platforms instead of buying IW.
This game will do well because it's a breath of fresh air for the franchise after all this years, i don't think crates have nothing to do with sales, i mean i even like them as long as i can get everything by spending time in-game (which is the case). Also DLCs have been there since the first modern warfare and people didn't care neither.
