Yeah, the ending is definitely open-ended, which is part of the movie's charm. Since it's a "wartime" movie, I'm thinking that Miyazaki wanted to give the movie some of that dreamy, fantasy quality that a lot of American movies around WWII had. The end is really what you make of it, and it kind of encourages you to give it a happy ending of your own. At least that's my opinion.
Btw, Zane/Josh, you might want to put spoiler tags around your last paragraph in that post. It's not really a spoiler, but it kind of is, too, if that makes sense. I didn't even realize until I had almost finished typing my response here.
Now I'm wondering if my response is also a spoiler. Hmm... What do you think?
(Oh, and thanks for the kudos, bud.
)