In Game of Thrones Season 7 Episode 2 "Stormborn" we see that:
Euron Greyjoy raids Yara Greyjoy's fleet, and manages to capture the current ruler of Dorne; Ellaria Sand, as well as her daughters, two of which are killed in the raid, and one is captured along with Ellaria and Yara.
In the following episode we see that:
Euron gifts Ellaria and Tyene (her surviving daughter) to Cersei, who are then quickly imprisoned and tortured.
This presumably leaves
without a current ruler, at-least until another steps up to take power. However, this does not necessarily mean that this kingdom doesn't have any current military power. Do the events mentioned above totally negate the potential power of this kingdom, or would it still benefit Daenerys to ally with what's left of this kingdom?
Also, given the current situation, who, if anyone, is next in line to take power in this kingdom. And, would this person be likely to ally themselves with Daenerys?