I am HOPING they are moving him to the nearby gazebo for Halloween...I believe the same thing happened a year or two ago, where it looked like his meet-and-greet was disappearing but it just moved. Then November 1, I believe they immediately transition him for Christmas (they did in 2012). The area around Duffy's usual meet-and-greet area looks totally different for Christmas, so it
would make sense for them to take everything down at Halloween if he's not meeting there during Halloweentime.
That said,
last year it was reported that Duffy didn't get a special meet-and-greet area for Halloween, so I don't know what's going on now.
If Disney contacted you in August and assured you that the meet-and-greet wasn't going away and then he DOESN'T come back for Halloweentime, that does seem rather underhanded to me. You'd think someone from Disney who would bother to
call you to explain the situation would know what was going on, so I don't know why they would give you misinformation.
(Regular Cast Members do often pass on incorrect information for whatever reason. If I had a dollar for every time someone said a Cast Member promised that Shellie May was coming to the parks soon, I'd be well on my way to buying my own from Japan.)
Anyway, I certainly hope Duffy is coming back and will be extremely disappointed and rather sad if he does not. And if it is confirmed, I will let Disney know my feelings, though given I'm far from their target audience for Duffy, they don't care what I think.
Either way, we should be pretty sure what's going on come September 12.