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Yes the ending will be significantly different.

For one, Euron Greyjoy is the big bad and is foreshadowed to release some sort of eldritch dark god entity into the world while binding one of Dany’s dragons, or summoning another moon meteor that brings another long night. He is also the prophesied Azor Ahai and Azor Ahai is bad and created the long night and white walkers by invading/warging into the weirwood hivemind and displacing the tree spirits. This is all foreshadowed by the story of the Bloodstone Emperor.

Dany won’t go full WMDs, instead she will have to kill and overthrow fake Aegon (young griff) who will be beloved by the people for ousting the evil queen Cersei who destroyed the sept of Baelor. So Dany will be seen as a tyrant but she’s not going to just massacre people. Tyrion is the devil in her ear though and she’s possibly allying with Victorian Greyjoy so she might become evil by who she associates with. It was always shown her invasion of Westeros would be terrible and involve mass suffering, with the Dothraki and Dragons that was obvious. Whatever happens with Euron, Dany will be directly involved.

Bran is going to have to resolve the issue of the white walkers by putting them back into the weirwood trees and driving the 3 eye raven and all other humans out of the weirwood tree hivemind to make space and right the wrongs of Azor Ahai.

Jon may be resurrected a lot more wolf like, his personality merging with Ghost while he was dead. This was ignored in the show. Also, it’s foreshadowed Jon might be the night’s king that the others are searching for, and they will resurrect him (not Melisandre) as a sentient ice wight like coldhands to lead them back to their homeland. Jon might become the leader of the white walkers and lead them to exile/peace.

I can go on if you like, we haven’t even gotten into the deep ones / merlings and their impact on the plot. They will be involved with the Euron plotline most likely, they currently have Aeron Greyjoy (damp hair), Davos and Patchface under their influence (anyone who drowns and comes back significantly different). They are the architects of the oily black stone cities of asshai and moat Cailin. They farm humans and breed them livestock, as seen on the thousand isles and the iron isles.

I wouldn't be surprised if the author saw the negative reaction, realized he was going to do roughly the same thing, and decided to just get circling the runway and churning out endless edgy side projects instead of coming up with something else.