Maybe they could have a digital display as well, but you would need a very complex, large, expensive and vulnerable system to show every riders place as is the case now.
I've been following the TT this year for the first time by logging on to the new and inproved iomtt.com live stream. And thought what a wonderful tool. I could imagine that, like the airport has screens with depatures and arrivals. you could have 2 or 3 screens next to one another showing the progress of every rider