Well you can strike me from the majority group.
Progression-wise Simpson is a flatliner. Save the cover positions for those who have potential, and eager to impress.
Right now I'd prefer Perch as the 1st back-up option, if you're looking at a straight-up defensive option.
Providing that we sign Debuchy (a balanced defensive-attacking fb, with a learning towards the attacking side) Tavanier would be a suitable understudy. Phase the lad into the first team, if the team is playing well - it's the best time to blood them.
Simpson loitering around the first team picture (as a go-to-guy, along with Perch re:back-up) stifles the progression of a promising kid like Tavanier.
Didn't think about Tavernier, makes sense tbh. Not like i'm desperate for him to say, like you say with Perch and Tavernier behind. Other fullback options too who can play both sides, it's not like we are lacking options if Simpson were to leave.
But if he were to accept a back up role, i would have no problem with it.