Well, it depends on what's necessary. Him not being that type of coach didn't stop him from building a top 10 defense the last 3-4 years. I think Allen's biggest problem was getting married to the wrong OC in Pete who is exactly the same type of influence and that's where the issue lies. If he can find someone to control the offensive side of the ball so he can only focus on defense the team will be fine.
With regards to them biting the bullet, I do think next year we should take our financial medicine ie, we shouldn't extend any contracts or try to make a splash FA or try to trade up in the draft. We should eat those contracts and not trade any future picks so if we have to move on in year 4 a new coach has far more flexibility.