Infinity Ward handled it quite well with Infinite Warfare thankfully - it was just a pity that not many people were around to see it. Activision have been very aggressive with BO4 MTX's and Treyarch not only rolled over and died for it; the quality of the content was god awful. I don't know whether Treyarch are just bowing to Activision or if the latter just choose their games to push more paid content but it's definitely more prominent in Treyarch games than IW or Sledgehammer previous.
Activision have lost huge revenue stream with the season pass element so they will need to find that elsewhere plus more. I would expect to see quarterly battle passes for £10 each or £40 which would cover it. Weapon skins and general customisation in the gunsmith will be rife also. As long as it's all cosmetic, doesn't make the game tacky and isn't in the users face constantly, it may be easy to ignore.
If IW maintain the brand and keep Activision happy, I think it could be acceptable like IW and WWII. If they buckle under the pressure like Treyarch, I dread to think of the state of the game come Christmas. Activision would be idiots to ruin this potential. They should take a leaf out of Ubisoft's RS6 Siege book.