Anyone else think that the Crannogmen and anyone else in that area have suffered some sort of Bermuda triangle incident and they've completely disappeared off of Westeros?!
EDIT:
Also, thinking on it, do any of the main lords have male heirs?
Tommen Lannister - Myrcella but it's highly likely they both die if we've read Maggie the Frogs prophecy correctly and assuming it happens.
Mace Tyrell - He has Garlan and Loras and another(?) - Garlan is not married yet, Loras is in the kingsuard and may not want a wife anyways and I'm not sure if there's another? Margaery would obviously lose her name with a marriage
Doran Martell - Arianne is the only daughter now, she'd lose her name if married.
Bran Stark - then Rickon, It's obviously likely that Rickon will have to carry on the name if Bran doesn't come back, of course, Jon could be legitimized potentially but we'll see on that. Sansa would lose her name as would Arya.
Euron - Has no kids, I'd assume this would go to a Kingsmoot, Victarion is most like to die, Aeron doesn't want it, I don't think Theon will ever recover and Asha is a female, so would lose her name.
Edmure - I think Roslin is pregnant isn't she? But it's not known whether it's a boy or a girl and it could die at an early age.
Stannis - Only has Shireen and she'd obviously lose her name upon marriage.
The Houses are all in awkward positions in terms of carrying on through that line. Let me know if I've made any mistakes though, did this off the top off my head.
And this doesn't take into account the precarious positions a lot of these characters are in at the moment and you can add Dany and Aegon, this is why it'd be useful to have him win the Iron Throne and be legitimate (It doesn't even matter if he is, as long as there's no proof either way) so that the Crown can be passed down through the Targaryens if they do win it