Are there any plans for a sequel and are there any future updates coming to Dusk?

An update adding HD models and Steam Workshop support is coming eventually, or dare i say SOON™. No words on a sequel as far as i know and i personally doubt there will be one in the works, before the full release of Gloomwood, another game by the same dev, which is more like the old Thief-games.

In the meantime, why not kill some time with some cool shooters, which have a somewhat similar vibe going on (if you haven't played them already):
https://store.steampowered.com/app/824600/HROT/
https://store.steampowered.com/app/1684930/CULTIC/