The new MacBook Pro seems to have an HDMI 2.0 port, not 2.1
The newly announced 14-inch and 16-inch MacBook Pro models have HDMI ports, but they have a limitation that could be frustrating for many users over the long term, according to Apple's specs page for both machines and as noted by Paul Haddad on Twitter.
The page says the HDMI port has "support for one display with up to 4K resolution at 60 Hz." That means users with 4K displays at 120 Hz (or less likely, 8K displays at 60 Hz) won't be able to tap the full capability of those displays through this port. It implies limited throughput associated with an HDMI 2.0 port instead of the most recent HDMI 2.1 standard, though there are other possible explanations for the limitation besides the port itself, and we don't yet know which best describes the situation.
There aren't many monitors and TVs that do 4K at 120 frames per second, and those that do are expensive. But they do exist, and they're only going to get more common. In fact, it seems a safe bet that after a few years, 4K@120 Hz may become the industry standard.