I, for one, am more optimistic.
First, plenty of cameras already offer 200mb/s+ recording onto sd cards. See, e.g. Panasonic GH4 (3 years old now), new Olympus EM-1 MK2. It's not a hardware limitation. SD cards exist now with write speeds approaching 90MB/s (that's 720mb/s). Plenty of headroom.
Furthermore, 4k60p can probably be done alright at 100mbps, especially if using h.265 rather than h.264 encoding (though obviously more is better). The Phantom 4 Pro from DJI records 4k60p at 100mb/s, for example.
So.. I don't think the bottleneck for 4k60p is necessarily storage. I think it's actually sensor read-out speed and the heat generated by current consumer-level sensors when called to read that pixels at such a high frequency.
The GH5 is supposed to record 4k60p internally. The Phantom 4 pro already does, and the Inspire 2 from DJI with the X5S camera (another micro4/3 sensor) soon will. So I would say there's a real possibility the AX100's successor will do 4k60p. Whether that successor will be launched this year or not is anyone's guess, though.