@simontatham I agree in principle, but sometimes "new and improved" really is better.

Often, even when it's time to change the foundations, it's possible to keep the old façade as a compatibility layer, as #SequoiaPGP has done with chameleon, https://debconf24.debconf.org/talks/16-chameleon-the-easy-way-to-try-out-sequoia-openpgp-written-in-rust/