So to be clear what does the 2.2 version HDMI get you. Just 4K content? Not sure I completely understand it.
HDMI 2.0 gets you 4K compliance, 2.0a adds HDR capability and the HDCP 2.2 protocol is for copy protection on 4K content.
I have a new Samsung SUHD display and the 4K HDR stuff streamed from Amazon on the TV app is just amazing. It's definitely the future of home video, IMO.
That said, there's not a lot of 4K or 4K/HDR content out there now, there are some 4K players and discs coming next year and, of course we have the inevitable format war between Dolby Vision and the SMPTE standard.
For the time being you might as well pick up a good deal on a non-2.0/2.2 receiver and enjoy it for a couple of years while you wait for the dust to settle.
Best,
Bill