Is it permissible for the Imam to intend to switch his status to a follower (muqtadi) of another leader during the prayer?

Primary text

The Imam's intention to follow another leader is invalid except in one specific situation: when the Imam appoints a successor, and then returns during the prayer to stand forward and become the Imam, building upon the prayer performed by his deputy. There are three narrations concerning this point, which have been previously mentioned.