Then right after the Breaking Bad intro screen we come back to present day, meaning the period right after the end of the fourth season, just prior to his 51st birthday. Mike is still in Mexico and hasn't heard about Gus's murder yet, so it's just days after the poisoning and shootout with the cartel.
We don't know what happens to get him to the point of needing a machine gun a year later, but we know it can't be good. Plus, he's coughing, so the implication is that the cancer has come back.
yeah- so I am guessing Skyler is out of the picture
looks like he is readying for the SHTF