Little update: I put in about $100 USD behind Akira, the open source interface design utility. I figured that's what another year of support for Sketch would cost me, so why not do the same for Akira.
I'm not so confident that this campaign will succeed (in which case I'll find another way to donate) because this may be a niche that's never really been supported on Linux operating systems, thus there aren't many of us around. Designers are well served on Windows and Mac, so why switch for worse software?
I only wanted to update to get back in the habit of writing and to encourage you to pledge. You won't be alone ;-)