It isn’t called out specifically in this proposal, but as a reminder to developers, id-tagging-schema will likely need to refrain from its usual response to tag deprecations. According to this proposal, crossing=zebra will not have exactly the same replacement tags in every region. For example, the replacement must include crossing_ref=zebra in some regions but most not in others, depending on legal expectations.
Furthermore, we’ll need to be very careful about any automated application of crossing=uncontrolled. In English-speaking countries, this tag was historically used according to the legal/engineering/colloquial definition before its meaning became corrupted in the non-anglophone world. Ideally, we’d review all existing crossing=uncontrolled and retag as crossing=unmarked or crossing:markings=yes before replacing anything else with crossing=uncontrolled, to avoid generating countless false positives that risk going another step removed from reality.
To facilitate this review, id-tagging-schema could institute regional deprecation rules, but that kind of scoping is currently unsupported. This is not necessarily a problem for the proposal, since it currently states that iD and Go Map!! don’t need to do anything differently if the proposal passes.