I think many of us here were upset when Tony announced his retirement from WDI. However I noticed a lot of speculation as to why he left. So first I am going to compile a short list of why he might of left and then ask for your opinions on it:

Hypothesis 1: Old Age
Tony was not young, in fact he was 66 years old at retirement, the common age of retirement in the United States. As such it is entirely feasible Tony retired because it was simply time to retire.
Supporting Opinion: Tony was 66.
Dissenting Opinion: For a man who appeared to love his job so much, one has to wonder why Tony would have retired just because of old age.

Hypothesis 2: Chased out by Management
I noticed some people speculating Tony was chased out because his fellow Imagineers were tired of him, and viewed him with little respect since Tony's involvement in the 1998 Tomorrowland. Blame has also been pointed towards fellow Imagineer Tom Fitzgerald, citing rumors of a fierce rivalry.
Supporting Opinion: Tony spent most of his final years working on small projects, suggesting management did not trust him with large projects. Tony in his last few months also voiced public criticism of the parks, notably on issues about the lackluster Imagination Pavilion at Epcot.
Dissenting Opinion: I would argue a lack of evidence that there was a rivalry between Tom and Tony, and point to the fact they worked together on both versions of Star Tours to great success. Also Imagineering put a tribute to Tony in place during the very recent refurbishment of Big Thunder Mountain at Magic Kingdom; suggesting they have a certain amount of respect for him.

Hypothesis 3: Golden Parachute
A hypothesis noted in a MiceAge article, suggesting Tony was given the option to retire gracefully before a round of layoffs would have forced him out the door.
Supporting Opinion: Disney has been doing a lot of layoffs recently.
Dissenting: ?

Any other ideas as to why Tony left? Do any of the ones I listed seem possible, or is it a combination of many factors?