There's no doubt that BSN will take a hit because they cover the main pro sports in Denver, but The Athletic coming in is going to hurt, no doubt.
As far as the coverage of the Avs with The Athletic...it just depends on who they get. Whoever that is will go a long way towards the quality of coverage. People can rip the knowledge of people at BSN, and seldom do--it's a free country, but since moving to a sub model they've made some very nice features (I liked the Ray Bourque one recently), and as I stated before--they still have AD, and whether or not people like him or dislike him, he's been probably the voice of the Avs since they came to town, when it came to sports writing.
It may not be any of the people that have been floated, they may lift someone entirely new, and that could be fun too. A good way for an unknown to make a name for themselves.