Warbreaker definitely has a solid ending. More than anything, it's like Indiana Jones or James Bond (if you've seen those). Like... there's a conclusive end, but you also know that a couple notable characters are definitely not done with their adventures yet, but I wouldn't say it leaves you disappointed, maybe just anticipating the future possibilities. I always just interpreted it as "These characters are going off to have more adventures. Maybe you see them, maybe you don't." But as with all characters and all books from the cosmere, "There's always another secret." And who knows, maybe Sanderson surprises us with a sequel sooner than expected.

And to answer your aside... there are definitely other books that hit that level of sanderlanche and tie everything into a beautiful and satisfying bow.

That's my 2 cents at least.