the fact that even if Gonzaga leaves the WCC, its not like the WCC (and BYU) isn't going to respond.  

Even if BYU stays in the WCC, the WCC will simply add 1-3 schools to replace Gonzaga (from Grand Canyon, Denver U, Seattle, etc). Some of those schools have some upside.   

The WCC might actually be a more competitive league without Gonzaga dominating (I'm not saying Gonzaga would not be a huge loss).

I think BYU will be fine if it stays in the WCC and Gonzaga leaves (and I've been a harsh critic of the WCC).

GCU Arena:

Denver U Arena