This isn't the last book.So this last book will have a different ending than the GOT tv show right???
GRRM has two more books planned. Winds of Winter (the one this thread is about) and then A Dream of Spring (which is supposed to be the final book, he's hinted that he can't rule out more).
But he says some of the endings for the main characters will be similar, but others will be completely different. A lot of the stuff that happened in the show can't happen in the books (for instance, there is no Night King in the books, so Arya won't kill a Night King that ends the White Walkers). Dany burning KL, Jon killing her, and Bran becoming King are probably broadly similar to what will happen in the books. The journeys there will be very different though.