I tend to think that if they do move on from Loomis by moving him to a new position or firing him, the most likely new GM would be Ireland so I'm not sure that would need to be done quickly since he is already running the draft stuff and is likely already part of the team considering who to interview for the HC job. Mueller who is also already on staff could be another possibility. Another possibility is that Khai Harley gets promoted to GM since he has gotten some buzz for GM jobs.
Honestly, I have thought for a few years that with Loomis hiring all these former GMs (Ireland, Meuller, and Dave Ziegler) he was preparing to move out of the GM job and promote one of those guys to GM.
So, I'm not sure that moving on from Loomis and hiring a new GM would end up being the house cleaning that many want.