We have a theory about who saved Mike at the end of Werner Ziegler incident in season 4 and becoming a thorn in Gus Fring's side, construction on Breaking Bad's meth superlab had to be postponed. Mike was in charge of that operation for Gus, but they have to lay low until the Lalo problem is dealt with. In the season premiere, "Magic Man," Gus offered to keep Mike on his payroll, but Mike refused (upset over how Werner was taken care of).
Removed from the action, Mike hasn't had much to do in season 5, but things have started to get more interesting. In last week's "The Guy For This," Mike had a run-in with some local punks, getting the upper hand on one in a physical altercation. Towards the end of "Namaste," Mike crosses path with the same group again, only this time things turn out differently. The punks overpower Mike, and one stabs him in the abdomen. After a smash cut to black, the episode cuts to a scene of Mike waking up in a bedroom; his stab wound has a bandage covering it, an indication he's received medical attention. Mike wanders outside and discovers he's at a mysterious complex (seemingly abandoned) in the middle of the desert. But who brought him there?
Based on what's known about Mike's role in Better Call Saul, a likely possibility is Gus. While the two characters are not in business together at this point in time, Gus is who Mike's been most closely associated with in the spinoff and it also stands reason to believe Fring is keeping tabs on his trusted associate during their hiatus. One way or another, the Lalo problem will be solved eventually, and the superlab project can resume. In order to keep things running smoothly, it would be better for Gus if Mike returned to his position. It's conceivable Gus had an employee of his follow Mike around to make sure there wasn't any trouble. When Mike was stabbed, someone obviously acted quickly so Mike could get proper care. Whoever this person was, they had to be close, eliminating Jimmy as Mike's savior (plus, the complex looks like something Gus would own).
One hole in this theory is someone as intelligent and resourceful as Mike would probably figure out he's being followed by one of Gus' people, and in most cases that would be true. However, Mike isn't really himself this season; he's torn up about Werner's death (evidenced by his request a postcard of the Sydney Opera House is taken down from a bar wall) and he's having family problems after he lost his temper at Kaylee. So, those things are affecting him. It's also possible whoever Gus sent is just really good at their job and knows how to stay off Mike's radar and get around unnoticed. Again, whoever rescued Mike was fast on the uptake, or else Mike would probably be dead.
It's important to keep in mind this is just a theory, and it'll be fascinating to see how this thread is resolved over the remainder of the season. Undoubtedly, more about what happened to Mike will be revealed in a future episode, answering questions viewers have following "Namaste." On-paper, Gus reads as the most realistic option (even if Gus himself didn't do this, someone in his operation could have), but Vince Gilligan has been known to throw some surprises the audience's way from time to time. Better Call Saul season 5 was already intriguing enough with Jimmy assuming the Saul Goodman persona. Now, Mike has an interesting story too.
Better Call Saul airs Mondays on AMC.