What I found is that it's just speculation. We know Elway has a history wanting and pursuing Vance Jospeh.
I guess we know that Ellis stopped us from getting Shanahan Sr. But...that's probably just not being an idiot.
It's also worth mentioning the fact that Kyle couldn't have been hired during the time of the interview because the Falcons were in the playoffs. Joseph was of the last batch interviewed in Denver. https://247sports.com/nfl/denver-bro...ahan-51081146/
There were also rumors that Shanahan wanted more power than John was willing to give up. He has a decent amount of power in San Francisco.
https://www.nbcsports.com/bayarea/49...el-power-49ers