Oh, since you know a great deal about networks then you of course realize that the majority of enterprise class network vendors still require a serial connection to do the initial configuration on their equipment? Oh, lets not forget about the SANs, tape librarys, fibre channel switches, the heat sensor arrays, industrial equipment... the list of equipment that still uses a serial port for configuration or data transfer goes on and on. I work with this equipment on a daily basis, there are at least a dozen other people here at the small plant I work at that use serial connections all the time to do their job.
Lets not forget, computers are not just meant to surf the web and look at porn.
And HDMI over DVI? Why do I want to send an audio signal to my monitor? Are you suggesting that we move the audio connection to the monitor, wouldn't that just confuse things?