Shanahan offense doesn't work unless you run the football well. So I assume if DA is fired and the Saints wants to retain the hottest offensive system currently in football, you have to retool that O.line as much as possible.
I mean, the OL was good when they were healthy. Assuming Penning continues to improve and Fuaga settles down after a rough stretch, I think you might like a younger upgrade at LG or even an upgrade at RG, but mostly the OL needs better depth more than anything else. I'm not sure that counts as a re-tool.