At first I figured that he was retiring, as he has worked in Imagineering 47 years, but he is really just resigning from his position and will now be a "part time advisor," as he put it. I'm not sure if that is a combination of 'moving on' and 'retiring' or not, but he certainly will no long lead the creative way for rides and attractions at Disney parks.
During his illustrious career, which famously started with him scooping ice cream on Main Street at Disneyland, Mr. Baxter has created many rides that we still cherish today. Those include Disneyland's Big Thunder Mountain Railroad, Splash Mountain, and Indiana Jones. He was the creative lead for Disneyland Paris, still regarded as one of the most beautiful parks in the world. He recently saw the Disneyland Resort through the massive expansion of Disney California Adventure, as well.
No news yet on what the future holds for Tony, whether that be a lot of relaxation or possibly the ability to consult on projects for other companies. That's pure speculation though, as his new role as an advisor for Imagineering could be similar to what Marty Sklar did for several years before his retirement. If you read his full resignation letter one thing is for sure, regardless of the reasons that led to his decision he is leaving with all the grace and well wishes for the latest generation of Imagineers that we would expect from him.