The "Game Series Sales" page, which records numbers in millions of units, has apparently been updated sometime recently to note that the Mega Man franchise -- that is, all the series together -- have reached (and likely surpassed) the 31 million mark. From 2013 to 2015, it had been sitting at 30 million, so notching another million during a period with little in the way of new releases isn't too shabby when you think about it.
Of course, the tipping point probably has something to do with the release of Mega Man Legacy Collection earlier this year, since it seems a few people liked it. Other re-releases, such as Virtual Console and PlayStation Store, probably helped, too. Just the same, we don't have any specifics, but it's good to see the number still growing.
Thanks to Roberto Zampari Caldas for the tip!