Yeah, I was shocked when I heard the news too. Funny thing is I suddenly found out when I watched one of the latest "Muppet Thought of the Week" videos on YouTube, that Kermit's voice sounded a bit more lower-pitched. It then occurred to me that maybe it wasn't Steve doing it; it was someone else. So then it dawned on me that Steve was somehow dismissed, and Matt now took over. And all because of an alleged personality conflict with both Disney and the Henson Family, particularly Cheryl and Brian, who according to them didn't get along with Steve.
I'm a bit mixed on the change. To be fair, the Jim Henson Company and Disney are both private enterprises, so they could do what they want, but at the same time it'll never be the same without Steve. Steve worked with Jim for almost four decades and he saw great potential in Steve, enough to eventually follow in Jim's footsteps and take over some of his signature Muppets, including Kermit, Link, Statler, and Ernie, including Rizzo. And it makes me feel sad that Steve will no longer continue Jim's legacy. And it also makes me feel a bit sad that we're seeing the end of an era; with Whitmire gone, Dave Goelz and Louise Gold are the last remaining members of the classic lineup, and who knows when they will decide that they will both no longer suit the Henson image. What a mess.