Interconnect technologies need mass, universal adoption. Pioneer used i.Link (Firewire) for jitter-free audio transmission. It only worked with Pioneer gear, and it has been dropped. Denon used Ethernet for their spec, and it's been dropped too.
There's also the issue of real estate; the back panel of equipment is crowded. HDMI can't be dropped at this point. So there'd be duplication of ports between the HDbaseT, and HDMI. Plus if a receiver can't convert between the two (which means new chips need to be designed) it'll be worthless.
It's nice that it uses RJ45 connectors. But it had better be designed in such a way, that if someone plugs Ethernet into it, or it into an Ethernet switch nothing bad happens at all. End users, for the most part, are stupid. Similar plugs for dissimilar uses are a bad idea. The PS/2 keyboard and mouse thing is a great example. (Did you know that with just a slight push USB fits into Ethernet? I didn't either, until I had to tell a company that their 48-port managed, power-over-Ethernet switch, had to be replaced because the secretary blew it up.)
