Unfortunately, I can't find the source, as it's been a long time, but I've read that in households that earn over $200k The Amazing Race is almost tied with Survivor for ratings, and they're quite good. It might be helpful around the renewal decision.

Also this season seems to have helped with bringing in younger viewers.

Season 27 had 0.6/3 rating in A18-34 and 0.4/3 in T12-17, while Season 28 had 0.7/4 in A18-34 and 0.8/5 in T12-17.

(Source: RJK, Spottedratings)

I will try to ask for data about the ratings in the T12-17 category for the recent episodes to see how many of the younger viewers stayed around.