“Which market segment is the one that is totally saturated with digital signage five years from now? (Is there a market where the gold rush is over and every new opportunity has been already taken?)”
I am not sure that there can ever be total saturation for a digital signage market segment. However, retail is probably the one where every segment of the market will have some form of digital signage. With technology continually improving, I believe there will always be some new way to incorporate new trends and return on investment for each retailer. I currently do not see any market where every new opportunity has been taken.