They are referring to adopting the Sequoia PGP library, which is written in Rust. There are plenty of benefits to using Sequoia which you can investigate now, no need to theoretically wait for the integration to happen. Not coincidentally, the RPM package manager also adopted Sequoia PGP.
First off, the mail references far more rust adoption than just Sequoia, but since you bring it up: here is how RPM adopted Sequoia in Fedora-land. There was a proposal, a discussion with developers about the ramifications (including discussion about making sure the RPMs built on all architectures), and there were votes and approvals. Costs and benefits and alternatives were analyzed. Here's a page that has links to the various votes and discussion: https://fedoraproject.org/wiki/Changes/RpmSequoia
Can't you see how much more thought and care went into this, than is on display in this Debian email (the "if your architecture is not supported in 6 months then your port is dead" email)?
> (including discussion about making sure the RPMs built on all architectures)
All officially supported ones. The Debian discussion is not about officially supported Debian ports, it's about unofficial ones.