Currently, we have DisplayPort 1.4 to HDMI 2.1 adapters (CAC-1085 and Cable Matters 201388 which probably use the RTD2173 chip) and HDMI 2.0 to DisplayPort 1.2 adapters (CAC-1331 and CAC-1332 which probably use the LT6711 chip).

Now we need HDMI 2.1 to DisplayPort 1.4 adapters. The LT6711GX chip can do that. It is backward compatible with DVI1.0, HDMI 1.4, HDMI 2.0b, DisplayPort 1.1, DisplayPort 1.2, DisplayPort 1.3.
http://www.lontiumsemi.com/product/list_1849.html

The adapter will be useful even for people that only have an HDMI 2.0 port or a DisplayPort 1.2 display because of the following:

1. The DisplayPort 1.2 adapters don’t support 10 bpc or greater even though HDMI 2.0 and DisplayPort 1.2 can.
2. The DisplayPort 1.2 adapters don’t support width greater than 4096 (such as 5K) even though HDMI 2.0 and DisplayPort 1.2 can (I’ve run into this problem)

For people with DisplayPort 1.4 displays (gaming or otherwise):

1. DisplayPort 1.2 doesn’t support 4:2:0
2. DisplayPort 1.2 doesn’t support HDR
3. DisplayPort 1.2 has less bandwidth than DisplayPort 1.4. Even though HDMI 2.0 has less bandwidth than DisplayPort 1.2, it can use 4:2:0 to support higher pixel clock than DisplayPort 1.2.

For people with HDMI 2.1 gaming consoles or other sources:

1. 4K 120Hz or 8K 30Hz (without DSC or chroma sub sampling)
2. 8K 60Hz with DSC or 4:2:0