Does anyone think that Daario staying behind, and Dany mentioning that Mereen and Dragon's Bay are now peaceful with the people on the verge of choosing their leaders, that this whole thing was a setup for an escape out of Westeros? I can't for the love of me fathom how the White Walkers can be stopped. Yes dragon glass and Valyrian steel kills the actual White Walkers, but with hundreds of thousands of dead zombies at their disposal, and an ability to raise the dead, the White Walkers never have to personally take to the field.
Jon killing one of them at Hardhome should never have happened. They could have all sat back and the result would have been the same. It was arrogance that caused it, and I doubt they'd make that same mistake.