I brought this up a month or so ago and never heard anything back. I too am fairly concerned with Twitch providing a fully working API even 6 months prior to the removal of the older APIs. I agree with @Syzuna, 6 months is a good transition time.
I am working with another company right now that is implementing an open API and have been working with them for almost a year as fixes and updates are made. They have a lot more endpoints than Twitch provides and handles a lot more data but my point is, testing out a change like this takes time and I would love to have a “finished product” to really test against and more than a month or two to test it.