Honestly, it's an interesting approach from Chelsea. They are basically spreading the cost of these players over very long contracts allowing them to work within the rules of FFP I believe, I do wonder if we'll see this repeated by other teams in the future. I guess it all depends on if it works out.
That said, they'll most likely still have to sell some players this January given the size of the squad. Apparently there's talk that Sterling's future at the club is far from certain despite only being a recent purchase from City.
Basically Chelsea have found a loophole in the FFP rules, one I expect a lot of clubs to copy.