So far, the most significant development surrounding Star Wars: The Mandalorian Season 2 has been the casting of Rosario Dawson as Ahsoka Tano. Filoni's new banner features Ahsoka with an ancient Captain Rex in what appears to be a Mandalorian-style artwork. They worked together in the Clone Wars and afterwards in the Rebels animated series. So it is possible that Rex will make an appearance in this season. Additionally, it was reported by Latino Review that Diego Luna will return as Kanan Jarrus for the second season. Luna recently revealed during a Q&A session at New York Comic Con that he is indeed back for more Mandalorian action. He also confirmed that Pedro Pascal will return as The Mandalorian character "Talpa" (or "The Tickler"). Pascal has already filmed two episodes for the upcoming season. The first one called "The Ghost" was released earlier this year and the second one will be released later this year or early 2020. So yes, it looks like Captain Rex will have an important role in the next season of The Mandalorian especially since Filoni included him in his banner image. We can only wait and see what other characters will show up this time around!