Where will the Iron Born Strike next?

[Veltigar]

Without defections, I don't see how the Ironborn could occupy the Reach. The population of the Reach must be ten times that of the Iron Islands.

I think there is a distinct difference between majorly defeating the Reach and actually occupying it. Long term, there is no way that Euron alone (even with all the magic he has) can take and occupy the Reach. However, the man is playing a different game than probably any other player out there.

A shortterm massive victory against the Reachmen would definitely work in favour of his plans. Eventually, they'll regroup around Faegon and/or Daenerys and push him out, but that doesn't mather to him. The Ironborn are just pawns for the man after all, they can all die after they aren't useful to him anymore.

After Euron's woops the Tyrells asses, the Ironborn will plague all towns and castles on the coast and riverbanks, but they won't be able to venture far inland. After declaring for Faegon, a part of the Reachmen will probably regroup somewhere like Horn Hill, which is about as far removed from the coast and riversystems as one can be in the Reach. From there they'll probably launch their campaign to wrestle control of the rivers back from the Ironborn.