I don't completely agree with your assessment.
Back line and goalie, I agree. Not much needs to be changed there. Midfield is where we disagree, I think Spurs needs a better player than Dembele. He's not bad, but I've never really thought he was a top notch player. Are any of Carroll, Mason or Winks going to be the answer? I'm not sure they would be, so you might want to offload Dembele and get a better option than him. You might also want to get some more depth at that position, if none of the younger alternatives are going to be good back-up quality for next season. They might be, but I'm not sure. I think Eriksen should be kept in place, along with Kane and Alli, but I think there needs to be better alternatives at that other wide midfield position and back up striker than Lamela, Son, Chadli. I'd personally keep Lamela and Son, and get rid of Chadli bringing in a starting RM, and a back up CF.
Additions:
Starting B2B midfielder-Pjanic, Nainggolan, Fabregas, Thiago A., Gundogan, Kante, Zielinski H. Herrera, Renato Sanches, Dahoud,
Starting RM: James, Hazard, Sane, Yarmolenko, Mkhitaryan, Dembele, Lemar, Mahrez
Back up ST: Batshuayi, Embolo, Benteke, Ramos
Subtractions:
Dembele
Chadli