Assuming the starting 11 remains to start the 17/18 season (Lloris, Walker, Toby, Jan, Rose, Wanyama, Moose, Eriksen, Dele, Son, Kane)
Formation 4-2-3-1
Strengths: GK (Vorm is a very solid #2 and Lopez offers even more depth. McGee impressed on loan and if he continues could factor into squad in the near future) RB/LB (Trippier and Davies could be starters on any of the Prem clubs outside of the top 7). Lamela (he can play any AM position and is a valuable asset to the team in attack and defense).
Weaknesses: Where is Dier going to feature? CDM or CB?? Winks and CCV are not ready for a large volume of first team football. Nkoudou, Wimmer, Janssen and Sissoko had very average 16/17 seasons. 
I believe we can sort out the 2nd team with only two signings: Bruma (or another young, inexpensive high risk high reward Winger) and Maguire (or another PL caliber CB who we can get cheaply and could factor as a backup without being upset). Adding Bruma would push Sissoko deeper into a Moose role (and tbf his build and abilities should do well there, he just needs to work for it). Adding Maguire would allow Dier to focus on DM in 4-2-3-1 and the RCB position in 3-4-2-1 would be up for grabs between Dier and Maguire. 
Notes: 
Nkoudou and Janssen have great attitudes and seem to be fitting in with the team. I believe they will both have solid 17/18 seasons and fill their roles admirably. No need to be replaced.
Sissoko is not good enough as a CAM/RAM as he played this season. A drop to midfield would really help him find his place in the squad and he would not need to be sold. 
A healthy Lamela and Dier will work with the first team often giving Maguire/Bruma and Winks/CCV the opportunities they need with the second team.
Trippier and Davies will also factor with the first team. If we wanted to sign Sessegnon and give him & Walker-Peters minutes we could.
I am not sure how NJie would factor at this point... considering we are reportedly signing another winger, he would be surplus.