With the higher gain ,and thus more directional , antenna needed to asure digital reception placing the broadcast antennas on one tower makes a great deal of sense. Having all the analog broadcast on the Twin Towers was done to improve coverage. If you have broadcast antennas in several location people will have to re-orient the receiving antenna as they change channels.horrors!Well,at least the people who live in the intermediate area.For distant viewers ,towers spaced a mile apart are no big deal.
Well if these transmitting towers are going to be highly directional then that really sucks for those who are on the back side. Not only is it not wise to put all brodcasting capacity at one site durring a possible time of emergency, but it also makes it a heck of a lot more attractive terrorist target. Imagine being able to knock out TV to a whole city like Denver from one small point.