Trudeau's approval ratings are okay and better than most premiers, but hardly sky high.  Also those who somewhat approve of Trudeau outnumber those who strongly approve 2 to 1, so a lot can happen.  Lets remember last year Brad Wall had an approval rating around 67%, today it's only 40% so a lot can happen in 2 years.  Likewise Notley two years ago had an approval rating over 50%, today it is in the low 30s while in Ontario Wynne was in the 40s two years ago while now in the teens.  In Newfoundland Dwight Ball was over 60% in early 2016, by the summer down to 20%.  One scandal, stupid mistake, or bad policy blunder can easily blow up one's high approval rating.