It's true, Lukaku has really been a very good reinforcement for Chelsea, I honestly could not imagine that he would move to Chelsea... But this machine sweeps away everything in its path, despite the fact that at Inter he got a bit lost and acted strangely. It's even difficult to push him away, a big man, in a word... Maybe they will quietly take the cup this year without any fuss, who knows...
He is a good player but I do not think he will be the difference for Chelsea. Manchester City and Liverpool are to strong teams that have better players then Chelsea. Liverpool have a very good striker Firminho or Jota and have been scoring high amounts this season. Manchester City do not have a good striker but I think they have enough depth that it will be ok for them. Chelsea are good but Lukaku is to inconsistent we saw it on the weekend where they struggled to win and Lukaku missed some easy chances.
I think lukaku is the striker they needed and he will bring a big help since werner stats last season were not good he misses a lot of chances i think in the striker position chelsea has an advantage but i agree with you city has many good quality players compared to chelsea.