I feel like people are over dramatizing the situation a tad bit. Don't get me wrong it is crappy of Disney to have cut it short (Especially given their reasons, such as the fact that the audience was too old?!), but people are acting like the show is already gone when we still have several hours worth of content to see, and we have no idea how well they'll pull off the rest of the show. For all we know this might improve the storytelling since a common writing tip is to cut out a portion of your initial draft to force yourself to write more efficiently. That might even already be in effect since season 2 has been a big improvement on season 1 in large part because there's a lot less filler, and it was probably written with the knowledge that they were being cut short (The news may only be a few months old but the crew were probably informed behind the scenes long before that).
Again, the company's actions are still worth complaining about, but I think we should still remain hopeful that the show will turn out to be a great complete package. At the rate the story's been going so far I can imagine a good conclusion being pulled off at the end of season 3 even if it is shorter.