Looks like Google is adding a message button on the Google Posts for local business profiles. Previously we saw a message button on the "updates" section, but now we are seeing then on the larger Google Posts section.
Claire Carlile posted about this in two different posts on Twitter, here is one of those sets of screen shots:
Claire said "there are many possible implications here - Google making even more of a land grab for customer interaction within the gated Googlescape, the requirement that businesses need to monitor this if they've switched it on and the need to use call tracking because Google's insights on calling is less than marvelous."
I guess this might get some local folks to test out using Google Posts again with messaging, if you have someone staffed to handle the messages. You would have to enable messaging in Google My Business and add Google Posts there as well.