I haven't really chimed in yet since the finale, so I'll do so briefly. I had intended to rewatch it and let it jell some more before commenting, but given real life, I won't have the opportunity to do so, or to read everything upthread, anytime soon.
Anyway, when the credits rolled, it was pretty obvious that the show would most likely be canceled. There was enough "ambiguity", if you could call it that, that seemed to leave the door open for more story, but Ahsoka's arc as a part of the Jedi was pretty clearly irrevocably over. (Cancellation is for the best anyway, as far as I'm concerned. No way would I have paid more
to add a premium Disney channel to watch another season of TCW.)
Indeed, the Jedi all but turned their backs on Ahsoka. They really came across as assholes. When they offered her a chance to rejoin, they completely marginalized the position that they had put her in. That right there was a major clue that it was coming to an end—or, more precisely, that any continuation in which Ahsoka said in effect "No worries!" would have been completely implausible and unsatisfactory.
As to the arc involving the assassin, I thought there were at least three important dangling threads.
The level of Tarkin's complicity, including whether there was really any at all, was one important dangling thread. Tarkin's self-confidence struck me as a narrative device that de facto excluded the possibility that Tarkin could have been mistaken or fooled by certain means of framing Ahsoka for the assassination of Letta Turmond. In particular, if Tarkin was not complicit, then, unless the security of the prison block was intact to the best knowledge of the military, I would have felt betrayed by the narrative itself. This is just part of who I expect Tarkin to be: when he struts badassery, he can back it up all the way, at least at this point in his career. Leading up to the events of ANH, all his past successes should reinforce his self-confidence, so that at the end he doesn't believe there is any need to evacuate the Death Star. Making him incompetent before that point would just diminish his character, not to mention the Rebels' accomplishment.
If Tarkin was telling the truth about the evidence against Ahsoka, then the question becomes how was it that he was fooled. Under the assumptions of the previous paragraph, it could only have been some extraordinary means, such as involving the Sith, as discussed upthread, or another fallen Jedi. The question of additional conspirators besides Barriss Offee, even if Tarkin was telling the whole truth, was never settled, either, and was another important dangling thread.
Any continuation which would just let those threads drop, by not having, or having had, the Jedi look into them, would have been completely unsatisfactory. Even if, say, Tarkin tried to argue that the problem was no longer a Jedi concern, but rather a military one, that wouldn't be so. The Jedi should be concerned with whether Barriss Offee really was the only Force-wielder involved in the assassination of Letta Turmond, as any additional people involved could reasonably still be among the Jedi ranks, or be Sith. Naturally, it would be logical in any continuation for Tarkin to assume the role of an inquisitor against the Jedi Order, to try to expose any other conspirators.
Further, unmasking the assassin as Barriss Offee hardly automatically explains everything. If the mere fact that she is a Jedi is enough for her to have been single-handedly responsible for everything,
Jedi should have been a suspect. If it really was only Barriss Offee doing all that, including breaking prison security without Tarkin's knowledge, then that could be touted as a clear and present danger to the Republic. It could form part of the cornerstone for Special Order 66, which if it did would surely be worthy of some screen time. As far as I recall, this rift between the Jedi and the military really began with the assassination arc, though Tarkin was always shown to be skeptical of the Jedi. What's behind this rift, including whether and how responsibility is shared between Tarkin and Darth Sidious, constitutes another important dangling thread.
The finale felt really rushed. I would have preferred that the final season spent less time on nonsense like the D-squad, and have instead devoted at least one more episode to wrapping up or at least addressing the outstanding issues I had.