I think Smiley will be fired and that's about it. Two things can be true about McDermott.
They overachieved given their roster quality (even with Josh Allen) this year making it all the way to the AFC Championship when Vegas had the Jets as the best odds to win the AFC East prior to the season.
They got completely out coached again against the Chiefs reinforcing all the doubts about whether McDermott has a playoff ceiling and is therefore oddly a victim of his own success.