Nah, they’ll ruin that too. They’ve already announced how they’ll bring in a bunch of the “popular” cartoon characters into the next two seasons, so they’ve completely lost me.
The big problem is nobody's confirmed anything. Rosario Dawson has heavily hinted, but "can't confirm" that she's playing Ahsoka. From her other comments it seems likely. I'm not shocked, though. Dave likes to bring characters from previous series back to continue/conclude their arcs in later ones. And Gideon having the Darksaber in the season finale is sort of a gimme that last characters we saw involved with it would likely come into play. Katee Sackhoff also hasn't confirmed who she's playing. Slashfilm "broke" both stories, by which I mean they found out actors had been cast and then jumped to conclusions. How likely those conclusions are is irrelevant. Jon Favreau didn't voice Pre Viszla in The Mandalorian, but someone else. And The Hollywood Reporter found out Tem was cast, and as whom, by "a source". On this everyplace else has quoted them as "fact" that he's back and playing Boba. Until there's an official press release from Lucasfilm, or we see it in the finished episodes, don't bank on anything.
That said, I'd have no problem with Ahsoka, Bo, or Rex showing up in The Mandalorian, depending on context and execution. My biggest gripe with the show so far has been the brevity of the episodes and the... inconsistent... tone. I've had reason to question one or another's directorial choices, so I won't fingerpoint any one "weak link". I'd be happier if they took a page from Sherlock's playbook, cor instance. Which many of us grew up with American TV seasons being 26-ish weekly episode with a break for Christmas, the BBC tends to concentrate their efforts more. I picked that show as one of the most notable examples of this, that many on here have likely seen. A season of three hour-and-a-half "episodes. For something Star Wars, I feel something that cinematic is the bar to shoot for, rather than jolty sit-com pacing. In particular because three episodes a season is -- wait for it -- a trilogy.

They could be filmed back-to-back/simultaneously, and then post-production done on each in turn, and their release based on that. Say, a couple months apart. We could have some real anticipation and feeling of
event. Like we used to with the OT and PT, or the Olympics, back when they
were still every four years.
The other part of what I said above -- how they're used...
HMSwolfe, you object to these characters from the aminated series showing up, but the show is called The Mandalorian and it's about Mandalorians (with one focal Mando, sure). His growth and evolution as a character is likely to involve some significant glimpses into Mandalorian society and recent history. No way around it -- in canon, that's Clone Wars and Rebels. Din was recued by Death Watch during the Clone Wars. Paz Vizla is very likely related to the Vizsla family in a not-too-distant way. The Darksaber was in both series -- most relevantly, being put in the hands of Mandalore's new leader right when they decided they were going to push the Imperial occupation out. That's the last thing we saw, from about a decade prior, before what we have here. The last person to hold the Darksaber before Gideon would be relevant to any story of how he got it. The characters who helped put it in her hands would be relevant to getting it back
out of Imperial hands.
People complain about the fishbowl effect, but this isn't that. Din is finding himself caught up in high-level stuff. Involving, not insignificantly, his own adoptive people. The people who have been involved with high-level Empire vs. Mandalore stuff before... Well, I'd be surprised if they
didn't make an appearance. Only way to avoid that is don't give Gideon the Darksaber. And it's too early yet to know whether that's a fan-service maguffin or actually relevant to the larger story that is to come in further seasons.