I just think an external would suffice just fine these days. We are only holding ourselves back at this point. I havent willingly touched a DVD in a year. Hell, once i watch a movie after a rip or download i typically delete it right away. No need for me to archive it.
I could understand leaving an optical drive if it was bluray but with DVD its basically the equivalent of leaving a floppy drive on there.
So what happens when you want/need to install Windows? FYI if you haven't tried, you cant install Windows from usb or external dvd drive... So if Apple wants to continue to have the customers that need Windows also, they will have to write the Mac firmware to allow usb/external cd drive Windows installations...