The cost of going back to WWI is that your cosmetics are very limited. Overwatch makes money off cosmetics, poses, sprays, emotes, and potg highlight intros. It's wacky, cartoony, and in a universe that it works with. Titanfall will probably sell cosmetics and burn card packs.
Battlefield is a war simulator. Outside of skins there is not much else you can ethically sell w/o drawing p2w cries. They sell the shortcuts, but I doubt they make a substantial amount on it. It's boring for most of us to buy our way past progression. Skins are only so appealing for this era without immersion breaking. Unless they do go to the future, I'd see BF Premium staying a thing. Even though I'm going to buy it, I wouldn't mind them giving it away for free a bit more early to keep the maps populated.
COD could easily give free maps with the direction it's heading. Their rng boxes, as bullshit as they are, have been a success for then. But I'm sure they'll still be greedy assholes.