I'm not sure anybody expects them to be the foundation of the side, but they would be an appropriate way to add squad depth. The two most successful English Clubs are Liverpool and Man City, they only operate a squad of about 20 senior players and then supplement with talented youngsters.
We currently have 23 senior pro's in our squad excluding Tanner and Rubin Colwill who still qualify as U21's. In addition Antwi counts as a senior player and we have 7 more senior players out on loan (Rinhomota, Adams, Davies, Evans, Bagan, Zimba and Ojo). In addition to Tanner and Rubin; King, Conte, Luthra, Turner, Denham, Fagan-Walcott and Kavanagh will, if they are still with us, become senior players next season.
We have a huge squad, we just need more quality guaranteed starters and fewer senior fringe players. Quality not quantity.