I think we have to assume the owner, president and GM are all pretty happy with Mackanin, even though he isn't guaranteed much. But they didn't hire him and they haven't forced him to change up the coaching staff (much of which, Mackanin included, dates back to Wade) so if they wanted a change they would have made it, at any number of moments in the past two years.
I think he's good. I can't recall many people thinking any of our managers were good, it's just that winning cures all. Wanting someone else is basically back-up quarterback syndrome. More likely than not there will still be someone else down the line, Wathan is perfectly set up for it and a total outsider would also make sense.
Until then I think he's running a good clubhouse and a generally overachieving or par team. Question is, again, what level of success next year gets him to 2019? Even if this year's club doesn't get close to 80 wins next year's still has to be in the mid-'80s, assuming they add the kind of talent it seems like they will.