Active recommendations are _intentionally_ not marked obsolete. The prior art for this is the Informational PEPs (see, PEP 1, PEP 8, etc). Looking through their revision history, most seem to have five or fewer revisions over the last 12 years. Informational PSRs are analogous to the Non-standards Track RFCs from the IETF, or to the Informational PEPs. They are things like coding standards and style guides and such, which won't break backwards compatibility if they're updated to stay relevant.

As I see it, our options are to follow the lead of Python / PEP and explicitly define and allow a reasonable scope for change, or to follow the lead of the IETF and adopt a long and rigorous proposal and recommendation and implementation cycle and set them in stone once they're completed.

Before we jump too hastily into the second option, we should remember:

It sometimes takes years to get something approved to even *enter* the IETF Standards Track.

Once a proposal has been proven useful, and approved by the IESG, it becomes a "Proposed Standard". By this point, there are often several real world implementations. It is "considered well-understood" and has recieved "significant community review".

[Per section 6.2 of RFC 2026](https://tools.ietf.org/html/rfc2026#section-6.2):

> A specification shall remain at the Proposed Standard level for at least six (6) months.

... then it can be considered for promotion to a Draft Standard. A this point it has to have "at least two independent and interoperable implementations from different code bases". At this point it's still not a standard, but it is considered reasonable for vendors to start deploying implementations "into a disruption sensitive environment." But it's not done yet. The Draft Standard can still be changed to solve problems found in implementation. And it has a waiting period as well:

> A specification shall remain at the Draft Standard level for at least four (4) months, or until at least one IETF meeting has occurred, whichever comes later.

... so now we're at 10 months to a year. But it's still not done:

> A specification may be (indeed, is likely to be) revised as it advances through the standards track.  At each stage, the IESG shall determine the scope and significance of the revision to the specification, and, if necessary and appropriate, modify the recommended action.  Minor revisions are expected, but a significant revision may require that the specification accumulate more experience at its current maturity level before progressing. Finally, if the specification has been changed very significantly, the IESG may recommend that the revision be treated as a new document, re-entering the standards track at the beginning.

... so after entering the (minimum) 10-month standards track to go from a proposal to a standard, if the board decides the spec has changed significantly, they may (and often do) recommend that it is treated as a new document and the 10-month clock starts over.

Judging from how things have gone with the four PSRs we've passed so far, the PEP approach seems a lot more pragmatic and reasonable to me.