Calum Chambers
The former Southampton defender was frozen out of the first team picture towards the end of last season, mainly due to the high number of games he featured in at the start of the campaign.
He is now most likely regarded as the fourth choice centre-back option behind Per Mertesacker, Laurent Koscielny and Gabriel Paulista, meaning he could find himself limited to just cup appearances next season.
Given his enormous potential, it would make sense to loan him out in order for him to fine-tune his game which would enable him to challenge for a regular spot at the heart of the Gunners defence upon his return.