Post Digitization, All Analog Signals will change to Digital. So, Quality of Picture and Sound will be enhanced tremendously .
Another Major Advantage is increase in Channel Numbers. Analog Signals have a limit of 100-200 channels but once digitized, one can get upto 500 Channels and Services.
A simple example of it can be Radio Services. Earlier we used to have AM Radio Channels and now we have FM channels whose Quality is much superior than AM Channels.