I like the authors remark on "source code FLOSS escrow" at the bottom of the article.

It's prolly hard to achieve legally, but the idea that a software is close source until it's no longer sold then automatically becomes open source would attract me as a potential user/buyer of the software: less lock-in in the worst-case scenario (being fully dependent on it wile company goes bust or decides to cancel the project).

Reminds me a bit of the https://kde.org/community/whatiskde/kdefreeqtfoundation/

<<The "social contract" ensuring Qt remains open-source is primarily maintained through the KDE Free Qt Foundation, established in 1998. This agreement guarantees that if The Qt Company ever fails to release an open-source version, or if the Qt project is neglected, the foundation has the right to release Qt under a BSD-style license.>>

It's not quite FLOSS escrow, but source code escrow is somewhat common among big enterprise software contracts. There are companies that facilitate this, e.g. https://www.escrowcompany.co/source-code-escrow/

I honestly do not think source code will be all that useful. Make it so redistribution, decompilation, reverse-engineering and reimplementation is legal after sales stop and that covers it.