I'd most likely not be impressed with anybody else trying to write the final novel from GRRM's notes, but if he was nearing completion on A Dream of Spring
before he died, then I'd welcome a job like Christopher Tolkien did with The Silmarillion
. An excellent novel and probably the best fantasy book I own. Even if it makes me angry sometimes that Christopher didn't include Dagor Dagorath. A hugely important part of the legendarium.