I would have thought it's the opposite, we need to sell the duds to raise money and also lower the wage bill by getting rid of the rubbish.
If Emery doesn't get rid of Mustafi and Xhaka (both on a decent sum I bet) then we have a problem and I'm not convinced we'll achieve anything, first thing for a manager is to be able to spot rubbish when he sees it.
We really need a major cull to get rid of all the substandard players we've horded over the years, it's clear we have quite a few who just aren't up to it (almost the entire defence and a lot of the midfield), no point working with players of this quality, it's just a waste of time.