New Receiver advice - 4k (1 Viewer)

So my old Denon receiver now has to be replaced. Can anyone tell me what I need to look for to have the best shot at the new receiver being compatible with 4k uhdtv? I don't currently have a 4k tv but probably will in a year or two. I see several that say they do 4k passthrough, but then I was told by one product advisor that to have the best chance of being compatible I needed to make sure it had HDCP 2.2, and that right now the only two manufacturers offering that were Onkyo and Sony. I was already considering an Onkyo 636..........any help or input is much appreciated.

HDMI 2.0 is two flavors.

18g without HDCP 2.2

Or

10.2g with HDCP 2.2.

Both solutions are half baked.

Wait till March/April.