Insurmountable perhaps is too strong - economically unfeasible may be better. But all the cheap fresh water most of Florida have now goes away in the near future. This is in addition to all the other problems listed in the article that other areas of the USA will not have. Israel may be a good technical example but not a practical example, it has to make the most of their limited land for expansion and geopolitical situation of being surrounded by enemies - they also do not have to care about financial considerations since the about 1/3 of the USA's foreign aid goes to Israel, the political situation in the USA means this foreign aid is pretty safe for the forseeable future.