It just so happened that the producers have only allocated five seasons for the popular TV series in order to wrap up the storytelling and finish on a grand note.
The fourth season of “House of Cards” featured some moments for Frank that include an assassination plot that almost succeeded because it left him unconscious for several days.
The possibility of Claire assuming the presidency by ascension looms high especially now that Frank appears to be ill. It would be a stretch for the series to hope that Claire would win the presidency over Frank in an election.
There are also rumors saying that Claire would be overtaken by her ambitions that she would also plot to kill her husband in order to ascend to the presidency.
However, all these plotlines are mere speculations pending the confirmation from the producers, the new showrunner, or any of the cast members.
There are also reports indicating that the debut episode of Season 5 of “House of Cards” will feature a tragic death which could leave fans to see something that they are not expecting.
It is not clear if it is going to be Frank right away or some other characters of “House of Cards” but it would be too early if Frank dies early in Season 5.