TurboQAM just enables the 256-QAM modulation on 2,4Ghz, same modulation that is used in the AC-Standard.Since its just a higher modulation, its a easy and save way to increase the bandwith (~30%). First adapter is already out ( Asus PCE-AC68) and in tests it showed this big increase. So there will be more adapters in the near future I think.
Would be great if Intel would include this feature (optional?), because I used their WiFi-adapters for years. But for such an increase I would change.