Brunette was on the shortlist for other teams last off-season, the Preds may not have had much choice but to match the term other teams seem to routinely hand out.
Anyway, coach contracts always have an out clause... you can fire them. Although you have to keep paying them. But that kind of money isn't very significant relative to player payrolls, so teams don't usually lose much sleep over exercising that "out clause" if it becomes truly necessary.
I just think from all the United Front chats and everything we saw from Trotz and Brunette heading into the season, they are going to continue to be joined at the hip for quite a while. It will take something truly extraordinary for Brunette's job to fall into jeopardy in the next few years.