Maybe not immediately, but Walt and Saul were at the vacuum place at the same time. Walt then went to the cabin for 6 months before coming back to ABQ for the finale. It seems unlikely Saul would still be around at that time.
Right, but that doesn't mean he was in Omaha yet either. Wasn't the cabin in Vermont supposed to just be a safe house or temporary setup for WW?
At any rate, what happened to Saul in between leaving ABQ and arriving in Omaha is probably either
a) going to be a future plot point in Better Call Saul, or
b) irrelevant
It would just be cool if they could find a way for the character to make an appearance in this movie without it seeming forced.