My line of thinking is CGC is a defensive coach. Expecting him to hire a DC with philosophical differences is kind of akin to expecting CPJ to hire an OC to install a pro-style. If CGC is coaching for his career, as I expect he is, I would think, as a defensive coach, he is going to live or die with *his* system, not someone else's. So I expect him to hire someone who at least shares the basics of his defensive philosophy. I mean, there isn't an infinite number of ways to construct a defense, so I don't think it will be *that* hard to find.
I also think it would be a bad idea to totally change defensive schemes. He probably needs to make a bowl next year and can't afford to give the new DC 2 years to fully install a new system.
But, we'll see. It's definitely going to be interesting.