Ah but you see, thousands of Jedi and Sith would not be possible in a live action show...
Since it is taking place in the time between Ep. III and IV, there would not be the opprtunity. Talk about non-canon stories... :-\
The thing is... Mr. Lucas is a slippery devil when it comes to Star Wars. I mean "Blue Harvest" as a code name to keep people away... the protection of the ESB script for the "Big reveal" until the last moment of shooting, and recording Voiceovers!
And people are supposed to believe that there aren't going to be any Jedi scenes in the TV show? Yeah, I'll believe that when I see it. ;)
About the Boba Fett Backstory... Sure it was repenned for AOTC... But remember... He was a kid in AOTC. Therefore it is not entirely unlikely that he could become an Imperial in the Timeframe suggested by the TV show. Sure he's a Mandlore clone, but what's to say that he can't join forces with Vader and Sidious to exact his revenge for his father's death?