Yes, I agree with that, especially if you mean changed for ever in the sense of "LOTR will always be read the way Peter Jackson filmed it" or "P&P will always be read the way Andrew Davies adapted it". That's clearly not going to happen, but you could perhaps make a weaker case on the lines that all these adaptations - especially the ones that acquire a kind of permanence through being on film - contribute to our evolving sense of the books' meanings and possibilities. I think that's where I'd part company with calimac - if I understand him correctly - in that I think the whole reception history of the book is not only interesting in itself but does do something to change what the book can mean for us.