I really wished we could've gotten to see this. I'm a HUGE fan of the Mandalorian people, so anything Clone Wars did with it I was super excited about. A series finale that featured Rex (my favorite CW created character), Ahsoka (my second favorite CW created character), and Mandalorians is something I can only dream about. Plus more Darth Maul. You can't go wrong with more Darth Maul.
I know that Filoni and co are busy with Rebels, and we'll get a lot more of Ahsoka in her new book, but I would love this final arc to get the "Son of Dathomir" or "Dark Disciple" treatment so we can finally see what would've happened.