Like Aston I must say it was a great interview, thanks!
These days “sustainability” (as in demand for) seems to blend into everything, mostly in the tech sector it is in the hardware that it should be possible to repair it and it should last for a long time so it does not quickly end up in a land fill with rare earth minerals or cause other problems for planet or inhabitants…
In my mind it seems Open source is such an important component to keep software sustainable with not enough developers to meet demand so we should all work together and share freely and build on each others work.
With proprietary software I often find myself running buggy software (if you install it at release time) that you need to spend a lot of time to bug report and follow up on only to their work so they can charge you (again) for the new version with your problems (hopefully) fixed (and new ones introduced;)
With Open source software I feel there is more we and even if you might have to do more work yourself you could hire someone in the know which might adapt it for you.
Another classical problem is the “embrace and extend” where you take something open source, extend it with some proprietary extension that might be nice to have, but instead of contributing them back to the community you keep them for yourself and sell the software as a proprietary solution that sadly seems to work if you are big enough…
Looking forward to reading your book, thanks for writing it!