Agreee with Tom, it would be too much to transform this TIP into a huge merge-and-repair all, so I'll label my suggestion as such, definitely not a veto. Anyway, this shows that it would be beneficial to have a forums discussion before posting a TIP so that things like these can be sorted out before.
On the topic of not breaking existing code - yes of course. A merge would have to consider upgrade issues as well, maybe someting like a compatibility api would be feasible.
