The fourth season will be called POTUSIn the same way Yes, Minister became Yes, Prime Minister. That show was Armando Iannucci's main inspiration for creating The Thick of It (of which Veep is loosely an American adaptation) so this will be done as a tribute.
In New Hampshire Selina caused her own 3rd place defeatBy refusing to meet with Maddox when he requested, Selina lost an opportunity to pick up his endorsement. Maddox may have only had 6% of the vote, but she only needed 1% to beat Thornhill and come in second to Chung. Maddox endorses Chung not to long after Selina refuses his request to meet.
The series will end with Selena breaking down in front of the countryAfter being pushed and pulled in so many directions and stonewalled by so many people trying to protect their own interests, she'll drop all pretense and tell everyone (in her own Cluster F-Bomb Selena style) how much bullshit goes on inside the American government.
Tom James will become president, and Selena will be his VeepAt first I thought James would become the new Veep and the main character of the next season. But he's just so cool that he'd be a Mary Sue if he was the main character, rather than someone for Selena to be jealous of. The polling will show that the only way for Meyers-James to win the election is if they change places on the ticket. Then Selena will remain Veep.