I can't find any data to back that up. On the contrary, it seems there's about 1.4 colonies per square mile in the U.S. Varroa has not been an existential threat to feral honeybees, and almost certainly has hit them much less hard than commercial honeybees because feral honeybees swarm much more often, which means they reproduce more often (thus get to adapt faster) and abandon old comb more often (which helps fight lots of diseases).

I'm not sure if the comment you're replying to is ironic, since it's repeating almost word-for-word my own honeybee rant, but Varroa mites drove feral honeybees in the US to extinction in the 1990s.

(There are lots of escaped, unmanaged honeybee colonies in North America, but it's unclear how many true feral colonies there are --- true feral colonies overwinter and reproduce).