I owned one of the original Courier HST modems. However, just like my automotive experience, we are rapidly approaching a modem bottleneck. Modems are getting faster all the time. PC's are getting faster all the time. Today's Uart's are very much like today's automotive beltways.
Beltways are routes around major metropolitan areas.
Usually, they posses an even number plus the two digits from the interstate they spawn. Most of these highways were designed in the 50's, when the volume of traffic was half of what it is today. Now, if you want to go when everyone else is going you run into a huge bottleneck. Speeds average about 20 mph, its bumper to bumper, and there are always accidents. We average about 4 to 5 rush-hour accidents a day.