I agree with many of the posters on here (and as it seems, the club) that Guéhi, Anderson and Semenyo would be an ideal trio of players to supplement the squad we currently have (despite having some reservations over Semenyo).
That said, here are 11 players I think we should keep an eye on if we find ourselves with a need for a player in their positions, as I think these players are ready to explode over the next year or 2:
Noah Atubolu, 23, GK, Freiburg
Givairo Read, 19, RB, Feyenoord
Yann Aurel Bisseck, 25, CB, Inter Milan
Ryan Flamingo, 22, CB, PSV Eindhoven
Diego Moreira, 21, LB/LW, Strasbourg
Anton Stach, 27, DM, Leeds United
Jack Rudoni, 24, CM/AM, Coventry City
Kees Smit, 19, AM, AZ Alkmaar
Maghnes Akliouche, 23, RW/AM, Monaco
Ruan Pablo, 17, LW, Bahia
Georges Mikautadze, 25, ST, Villarreal
with special attention paid to Givairo Read and Kees Smit, who I think will be superstars.