Receivers with HDMI
I doubt that Denon, Yamaha, or other manufacturers will be offering firmware updates to upgrade the version of HDMI on anything short of their flagship models. 1080p, in perticular, requires twice the video bandwidth of 720p and 1080i so there may be hardware limitations with the current crop of receivers.
You concerns about HDMI are valid. You might consider buying a Denon 3805 for about $700. In a year or two, 1080p displays and sources will actually be available and HDMI will be more mature making it a good time for a receiver upgrade.