Are the Martells in danger of extinction?

[HouseFossoway]

Oberyn and Quentyn are dead. Doran probably won't have any more children. We don't know of any other distant martells. Which leaves Arianne and Trystane.

Both of them have left the safety of Sunspear, and have gone off to fangerous places. Trystane is going to King's Landing, where there would be numerous factions that would want him dead (Cersei has already demonstrated this, and the Tyrells would want him dead so that they could marry Myrcella to Willas). Arianne is going off tot he midst of fighting, where there would be many ways for her to meet her end.

I'm not saying that the Martells are going to go extinct. But I think that there is a definite chance that the Martells could be gone by the end of the series.

[James Steller]

Who says Trystane is going? Doran called out the ruse and only pretended to go along with it. Trystane will likely stay in Sunspear while the Dornish go to war.

[Lord Lannister]

Just another example of the families that have been ruling Westeros for "thousands" of years having no relatives beyond the main branch of their family somehow. Stark, Targaryen, Baratheon and Arryn are all other examples of this.

[John Doe]

Of course they have other relatives. Manfrey Martell, the castellan at Sunspear, is a cousin of Doran. And it was never said he was the only one, or that he had no descendants. 

[dariopatke]

No more than Tullys, Starks, Arryns, Baratheons and Greyjoys.

[HouseFossoway]

I just realized that some of the sand snakes could theoretically be legitimized.

11 hours ago, John Doe said:

Of course they have other relatives. Manfrey Martell, the castellan at Sunspear, is a cousin of Doran. And it was never said he was the only one, or that he had no descendants. 

I forgot about him.