If he's content with being 3rd choice for now (that's where I'd have him at the moment, way ahead of Lindelöf), I'd like to see him stay and us to sell Varane. The latter is really injury prone and we're giving him almost twice as much in wages as Maguire.
It seems like we're buying an RCB next summer either way, so offloading Varane with astronomical wages and 1 year left on his contract seems like the right decision in light of his injury problems. Maguire then can fight for his place with the new signing, whoever that may be.