The armony and the balance of the team depend on how you are smart to rotate the players which you have.
There are managers capable to work with 16 players (Guardiola) and managers which prefer to work with a limit, like Conte this year. Ok, this year has been simple because of no european competition, but when he was in charge at Juventus, used more or less the same players because has a limited faith.
I'm sure, following how has worked this season, next season Conte will not change and will not be in favour of rotation before a CL game or generally before an "easy game". Players like Kantè, Azpilicueta, Cahill or the new starter on defense, David Luiz, Kantè, Hazard, the striker, Alonso will be ever into the starting XI.
I say this to think about our situation. If Wilshere will remain with us next season, signing or not the new contract, we will have Coquelin, Xhaka, Elneny, Cazorla (ok, he isn't young, at the moment is injured, but when he will recover and will start to train like the other players, will be not happy if he will not be involved), Ramsey: five players for two places. Five players, for two places and a desperate need of an upgrade to help Xhaka and the team to perform well.
The situation could be attenuated with the EL campaign because of the low qualities of the opponents until the Quarter Finals, but is the Premier League to remain important.
Arsenal can't sustain five players in two positions, especially if you need an add and the quality is not balanced, if two of the five players are now not good enough to perform, one is a normal player (Elneny) and one is shit (Coquelin).
I would prefer to keep Xhaka and Ramsey, keep Santi into the 25-men squad and sell the others to rebuild this section of the team with quality players with a mix of experience and young ages.
An example? Matuidi and Fornàls.