> My only add here is that I implemented SRFI 88 & 89 for my own system.
> 88 is optional and enabled with #!srfi-88  and can later be turned off
> with #!no-srfi-88.  They set/clear a parameter associated with the port
> being read, in a manner consistent with #!fold-case and #!no-fold-case.

That's great :) You were way ahead of us.

Would it be a farcial idea to write a new keyword SRFI that unifies all
the existing keyword standards? It would keep the three old syntaxes,
but disallow forms of them that step on each other. It would not
introduce any new keyword syntax. #! reader directives could be used to
turn the three syntaxes on and off in any combination; implementations
could pick which ones are on in the default syntax so their current
behavior doesn't need to change. Procedures to work with keywords could
be copied from SRFI 88 and/or elsewhere, or left unspecified.

If someone needs to take the blame for this unification, I can take it.
Or we can do without a new SRFI and just try to work things out
informally. But it would be nice to advance somehow, given that there is
so much agreement (mainly the placement of the colon is different).