This is a completely hypothetical question - I haven't even finished my manuscript yet.
I'm just wondering if people would be willing to change the ending of their novel if a publisher asked them to or would you want to keep the original story that you created?
It would depend on what was suggested.
My immediate response would be to ask further questions of the publisher so I could understand the reasons for the suggested changes.
Then I would think about it.
If it made sense (or I could admit it was much better) then I would roll with it.
But if I really didn't like the idea I wouldn't want to put my name to a novel that I would feel embarrassed about. I can't imagine that an experienced publisher would suggest something that awful though.
Maybe if it got to that point, a second (and third and fourth) opinion would be needed.
Good question I haven't really thought of it that way. I suppose what I would do is try and make it the best ending I can possible think of before I show it to them. If they think a change was in order I'd listen to them as they have a lot more experience than one do. However if the ending of a story was personal to me and something I must have in my book I would fight to leave it there or I'd try and alter it and move it into a different scene in the book.