need an OL coach. So hiring Grimes doesn't necessarily mean anything regarding Empey. (Obviously Grimes could bring in his own OL coach to replace Empey, but Grimes himself won't be the one filling Empey's position.)
And I don't mean to be dismissive of your point--you are right that the extra assistant coach everyone will have next year will shake up the way things are done. You could very well be right that OCs may end up mostly not coaching a position on top of running the offense. That would make a lot of sense for a new OC in particular (I'm sure it would have helped Ty).