This is definitely the end of Maguire.
Evans is a great stop-gap, until we're ready to properly invest in centrebacks next year. He's just as competent in the air while being better on the ground. He also counts a "club trained" home-grown player for champions league. Lastly, nobody will whine about him not getting adequate game time as he's in the twilight of his career.
I suspect the depth-chart for CBs will be this:
LCB: Martinez, Lindelof, Shaw, Evans
RCB: Varane, Lindelof, Evans
I think those less important games where we rest our starting 11 CBs will be Lindelof as LCB and Evans as RCB. I think we won't see Shaw as much at CB as we did last season, even though he played well there because we now have actual CBs who are also good with the ball on both feet.