I'm going to get the Incredible but my next phone after that will undoubtedly have an hdmi port. With a 32 gb card I can load several full DVDs 3-7 gbs per dvd) on there when I make trips or remotely access my home computer and download a movie from one of my several external hard drives and play them on a tv wherever I'm at if I choose to.
Here's the thing, people laugh about having only one device to do multiple things but we are definitely moving in that direction. Phones now are powerful enough to run full featured word processing and other productivity software. I'm looking forward to the day I can plug my phone into a docking station at work and take advantage of the hdmi and usb connection.
We've already made evolutionary progressions in cell phone technology over the last 15 years. It's grown from a phone to combining a PDA, email, internet, games, media, etc. Hell, many people like me use it as their alarm clock in the morning too. As processing, battery, and storage improvements are made, it will start to replace full size computers.
Maybe I'm just always looking to get the most out of my electronics but HDMI seems like a no-brainer to me.