Bronco's D may well have the best secondary it's ever had over the next few years. All that, with Mangum at QB and a pool of talented WRs and RBs. If Mangum can stay healthy, the next few years really do have a lot of promise.
The past 4 years of 8-5 seasons are very directly tied to QB issues, some of which is Bronco's fault, some of which isn't. I think those issues will go away over the next few years (again, assuming Mangum can stay healthy).
I think the future is bright for both the football and basketball teams. Which is why firing either of the coaches at this point would be a mistake, in my opinion.