Priority number 1 should be to address the front office.
You can go looking for coaches all you want, but until we get better drafting on a consistent basis, this team will continue to be doomed to mediocrity.
There are several guys you could look at, but the guy I like most is, Brian Xanders out of LA. He's a personnel executive for the Rams, but before that, he was the GM of the Broncos that built the team that went to the Super Bowls and eventually won one. He seems to have success where ever he goes. I think they only way you get a guy like Xanders is if he has the ability to choose his own coach. This year would be an ideal year for that because Xanders could keep Gase with almost no pushback from the players while he evaluates a coach he may want to replace him with.
If I remember correctly, this team, based on its roster was seen as a bottom 5 team in the NFL. Many publications had us as the worst team, and that was with the idea of Tannehill starting every game. The team is obviously not the worst in the NFL and considering that a team, many saw as devoid of talent, has had numerous key injuries and is still 7-7 is solid at worst. While the staff does need improvements, especially in Gase giving up playcalling and a new DC, the biggest area of deficiency is the talent on this team. Basically, expect Gase to get at least another year...Philbin was given 4, Gase will be given a 4th.
I would also expect Tannehill to be the QB going into the season next year. There really just isn't a lot that seems like an upgrade in this current draft class and we won't be in a position to draft a Heubert is he is to come out. Hopefully, this front office has enough foresight to take advantage of this talent-rich defensive draft.