GKs - maybe Lopez in and Vorm out, so that we have Lloris, Lopez and McGee. I'm not too bothered about this though. At most its 1 in, 1 out, or net 0
In terms of CBs, given that we seem to be playing 3 at the back more than 4 at the back, I think we need strengthening there. Dier isn't a CB and also if you start to count people twice for two positions (Son, Dier, Davies etc), then you could convince yourself that you can get away with a very small squad. So personally I think we need 4 senior CBs in the squad in total to cover the 3 CB positions, with Dier, Davies or CCV being emergency cover. (Dier I count as one of our two DMs, Davies as one of our two LBs). Given Poch used Wimmer a lot the year before last and he did well, though didn play Wimmer much at all last year, I'm not sure what his future looks like - so this is 1 or 2 signings needed depending on Wimmer and such that we have 4 senior CBs.
FBs - we're fine.
DMs - fine, Dier and Wanyama
AMs - fine, Winks and Dembele, though I'm concerned about how much Poch seemed to think he had to nurse Dembele through the end of the season. I dont rate Onomah and he certainly isnt ready for the PL or CL
Forwards/attackers/no 10s - we have Son, Alli, Eriksen, Lamela who are all decent enough. None of them have genuine pace though or real x-factor type skills. Sissoko should be sold, GKN is too raw and given he plays as a winger though we dont, feels like an odd signing - I'd loan him out for the season next year to a PL team. 4 players aren't enough to cover 3 positions when we might play 60 games next year - I therefore think we need to add two players here, though with some degree of flexibility such that one of them (who has some pace) can also cover CF. Adding two might seem a lot however given Dembele issues mentioned above, I can see Dele or Eriksen playing CM for 10-15 games....so given one might cover CF a bit plus these two dropping deeper sometimes, its not necessarily like adding two pure attackers
CFs - Kane and Janssen, fine subject to getting an attacker with some pace who can also cover here
There you go....its how I get to needing 3-4 signings this summer if we really do want to be competitive!