What if Jamie arrives at Winterfell and informs everyone that Cersei has reneged on her deal. He also informs them the Golden Company is on the way from Essos. That might influence the Northern / Daenerys armies to attack Kings Landing. Perhaps Jamie will plead with Cersei one last time to see reason and Cersei will tell Qyburn to "burn them all" which causes Jamie to become the Queenslayer. Kings Lands is gutted by Wild Fire fulfilling the vision from the House of Undying and the prophesies regarding Cersei come to fruition.
Rohlin_the_Wretched replied to Little Scribe of Naath's topic in General (GoT)Easy. The wights can't swim ... they also can't drown because they are dead. It wasn't they couldn't go into the water, it was just they would sink to the bottom. Which is perfect for getting chains on the dead Viserion, just they are stuck at the bottom. The Night King can replace his army almost at will, so it doesn't if a few wights are stuck at the bottom of the lake. As far as all the complaining about the Night King, not taking out Drogon and the army's stop at Hardhome Depot, there is an explanation that fits most of your complaints. If the theory about Bran is correct and he is the Night King, then Bran King could have had a vision of Viserion being killed by his spear and plummeting into the lake. This would explain why he changed targets at the last moment and how the army had chains to pull Viserion out of the water. Once the Walkers took Hardhome, the Night King could have had the chains forge there and brought with them to the lake. It would also explain how the army suddenly appeared after the wight was captured. It might have also been a trap set by the Night King because he had a vision of Jon trying to get a wight.