Welcome to WDWmagic, it's nice to see another fan of the Fox and the Hound.
To be honest, it's pretty lucky we even got a sequel, or midquel to be more accurate, at all. The Fox and the Hound wasn't particularly popular back then and it still isn't today, so it's kind of puzzling as to why Disney made The Fox and the Hound 2. This relative unpopularity of the original can clearly be seen in 2 as there are several creative liberties taken to expand the world of the film. One of the producers even said that they took a lot of creative liberties because the first one wasn't well known. And as a response to your point about a "cliffhanger," there really isn't one because the story was wrapped up nicely with Tod and Copper coming to terms with being separated forever with Tod and Vixey going to live their lives in the forest and Copper continuing to be a hunting dog.
I admit would like to see a third movie as I really would like to see Tod and Vixey's story continued, but it is never going to happen. The first two films aren't well known enough to warrant a second sequel. Even if they were, it would still be unlikely given today's Disney animation's reluctance to make animated sequels to any movies other than recent ones like Frozen and Wreck It Ralph.
Sorry if you're disappointed, but that's just the reality