The source as stated came from wdwmagic's forums from Spirit. Yes he knows what he's talking about (and other insiders like Martin and Lee back him up as a very trustworthy source of Disney info). Obviously anything can change at Disney at any time, but people familiar with him will tell you he has a very good track record with reporting current events and info.
Just a few more details. Imagination is apparently finally getting some attraction attention, so it isn't closing like WoL. There will be changes coming. When I have solid info on the scope of them, I'll pass them along. I believe this is substantial, but not as much as most of us would like.Imagination will be down for all of next year and Captain Eo will head to the cosmos for good;And while I can't find the post (likely in a different thread), Spirit said the new Imagination project apparently might involve Figment (in what size of a role is unknown).Tony has been spotted with the group working on this. I sincerely hope he can consult and have a role as it's what he wanted most in FL the past decade.
Either way, until things change, Spirit has confirmed that there's plans to overhaul the ride and redo it. No one knows anything beyond what he posted above, whether it's an expansion of the current ride's theme, more akin to the original, or something entirely different. But it sounds like it's not being shuttered like WoL.
The original thread is here, though the quotes above sum up the relevant info about Imagination from that topic-
Two Spirited Quickees... | WDWMAGIC - Unofficial Walt Disney World discussion forums
He also creates threads about his thoughts in general that he posts in and he might have some info to post there in the future (though he might just create another new thread about it). He posts info as he gets it. If they're planning on closing the attraction sometime next year, we'll probably see some more info from Spirit soon about it.