TurboQAM is I think a non-IEEE standard feature. Intel cards strictly comply to IEEE standards. Even if you buy a Broadcom chip, I don't think it'll work though since I think TurboQAM works on 2 identical routers with the other one on wireless bridge mode.
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.
From my point of view, its just the name "TurboQAM" (Trademark) that is proprietary. Would be very strange to get a patent on a 256QAM modulation?? Link: TURBOQAM - Reviews & Brand Information - BROADCOM CORPORATION Irvine, CA - Serial Number: 78206985
IMHO Intel could just name the option "256QAM" or "Super-Duper-High-Speed-WTF-Technology" and everythings fine. ;o)
Since there is no Centrino 6300 with M.2 (NGFF) form factor with three antennas or they don't get this 256QAM modulation in their drivers, its a big step backwards for me and many other customers.