Well for a Cech replacement you already have Courtois who has the position locked down and should become a club legend in time.
RB there's plenty of options like Aurier, Pereira from Nice/Porto and Cancelo from Valencia, all capable of bursting forward with technical skills although Cancelo shies away from his defensive duties and would be a better wingback.
The arrival of Rudiger bodes well in game and you've already got Christensen too who should be kept till he retires as he could mirror Terry I believe if given the chance. Van Dijk is another option to bring in.
Left back for me personally is a big hole as I don't think Marcos Alonso is quite up to stretch and he also isn't pacey either, Alex Sandro is a world class LB/LWB and should slot in nicely, you can also look at the likes of Grimaldo and Gaya who are both younger and though not quite world class yet but have the potential to be.
Pretty sure everyone knows by now how much Kante resembles Makelele. I rate Bakayoko and he's a fantastic addition to the squad, in a similar mold to Essien too. You've still got the likes of Fabregas, Baker and Pasalic who can turn out to be really good if developed. To fill the goalscoring gap in MF left by Lampard I think few fill it better than Sergej Milinkovic-Savic from Lazio, I've used him before this year and he's a monster. 6'3" and just destroys everyone in sight, great goalscoring ability too and can also play AM.
Hazard is pretty similar to Joe Cole back in the day so I think you're covered there.
Morata is another great addition and Batshuayi has shown real quality in real life and is already a fan favourite, and he also came from Marseille just like Drogs. Don't really think you'd desperately need another addition in this area, Pedro can cover too if required.