If a recent listing on the Steam Database is to be taken at face value, more Mega Man 11 could be on the way. On October 10th, Mega Man 11's Steam Database page saw the addition of a post-release branch titled "8ing".
According to speculation, the branch name is a direct reference to 8ing – the Japanese video game developer who worked with Capcom on Tatsunoko vs. Capcom, Marvel vs. Capcom 3: Fate of Two Worlds, and Monster Hunter 3 Ultimate. The existence of the 8ing branch suggests Capcom have outsourced, or are collaborating with 8ing to develop future Mega Man 11 content. To date, 8ing have not worked directly on any Mega Man game.
Beyond the "Wily Numbers Instrumental Tracks" pre-order DLC, no additional Mega Man 11 content has been announced by Capcom. However, it's worth pointing out that the game does check for DLC upon boot-up. So if additional content is planned/currently in the works, Mega Man 11 is already primed and ready for it.
So hopefully this will amount to something. I mean hey, I know I could go for some DLC. (second playable character, please) I'll keep you posted either way. Thanks to Hanumachine for the tip!