I loved the show so much, the concept and all..just amazing...but I feel like a single season would have been more than enough since premise being all about the rise of the designated survivor and finding the conspirators who caused destabilization of the government. With a single season, should have been more than enough or 2 at the most. However, dragging the character for more seasons, in building a new political story and all, just made the show feel like any other political show, which made the show boring at the end, even thought the concept was truly fresh and new.
The Korean version of the same show was very successful cause they realized this problem and hence only stuck to a single season and this not only made the political dram more captivating...it also meant no trying to pull story lines or suddenly introducing new characters or trying to pull conspiracies or theories when they dont need to be (making k drama get a rating of 4.9/5).