I believe it would be useful to start thinking of the problem in terms of a transition plan from what we have today and what we would like to have tomorrow. It is not clear to me exactly what we would like to have tomorrow, so settling that would have to be part of the plan as well.
Indeed. For IDNA, I think the current specification serves fine for today and tomorrow, so nothing needs to change at all.
What is much more relevant is how further constraints in the registry (beyond those imposed by IDNA) get implemented. Only when that is sufficiently settled and deployed, considering *updates* to IDNA should start.
Regards, Martin