Black Ops 4 wouldn't run well on the Switch.
COD3/World at War/MW1/Black Ops didn't run well on Wii, but they still sold over a million a piece.
I think the big difference between those games and Black Ops for is that... They kinda ditched the Singleplayer to the curb with Black Ops 4.
Online isn't exactly the Switch's strong point, especially in handheld mode where it has to dangle off another mobile device.
I'm playing the devil's advocate here I know, but I don't think COD has any chance of even running on the Switch. And let's face it, most other modern (PS4/XB1) triple-A, realistic graphics games can't either. Sports games are significantly less demanding, so they can run cleanly.
If a game is a 60fps title on Xbox One, I don't see why it couldn't run on Switch at say... 30fps.
Doom/Wolfenstein are an exception because their engine (ID Tech) is probably the most scaleable engine in the industry (allowing Doom to run on a potato). ID software are outright wizards when it comes to their tech, and are very experienced veterans in game development (though I'm not trying taking any credit away from the Switch itself to be able to rum those games, as you have to remember, that this is a handheld as much as it is a home console).
The porting wasn't done by ID Software though, it was done by Panic Button.
You are correct that ID Tech 6 is extremely scaleable... However, the counter argument is that Doom/Wolfenstein has a significantly more demanding and complex rendering pipeline than say... Call of Duty which has never been known for it's visual fidelity since the CoD 2 days.
In general, if a game is 60fps on the Xbox One, then I don't see why it couldn't be 30fps on Switch+Downgrades.
If Switch were to get an COD, I think it's be a remaster/collection. I'm kinda surprised there hasn't been a Modern Warfare collection yet.
Give it time... I wish Activision would get off their posterior and give Modern Warefare 4 the Xbox One X enhanced treatment.