While I agree with the body of your reply... I'm getting no indication that your title has much to go on.
Nearly all my friends around here are either Niner or Raider fans... I haven't heard a single Niner fan express doubts about Shanahan... other than what's typical among all fans, including us - "Why that play there?". IOW, they have full confidence in him.
the BIG issue I hear from Niner fan friends is JG.... I believe ALL I have talked to have serious doubts about him going forward. This year the #1 opinion among them regarding the problems they are having is injuries... wise IMHO.