raise the long dead, and they don't have to of died by the hands of one of the already undead, Westeros is hosed. Because:

(a) As you say, the crypt of Winterfell is full of potential combatants, so the dead will be able to attack both from within and without. With no defensible position, Winterfell will get overrun extremely quickly.

and

(b) Can't recall if it was at Dragonstone or Kings Landing, but one or the other had skeletons of long-dead dragons. Once the Night King adds those to his horde of Wildlings, Dothraki, Northerners, and Unsullied, I'd say the Iron Bank will no longer make loans to the living humans.that are left. Too much risk.

Winterfell better just hope raising the long-dead isn't one of his superpowers.