The difference is that here the Wizards Rep isn't talking about future plans, he's talking about something that (didn't) happen in the past. So, barring the very unlikely possibility that he was misinformed, either what he's saying is true or he is lying.
Honestly, I expected 5e to be announced. I'm a little disappointed that it was not. But it wasn't, and when the Wizards Rep indicates that there was no cancelled announcement, I have no reason to doubt him. It would seem that Morrus' "reliable source" simply got it wrong. It happens.
This is important to keep in mind for when 5ed is inevitably announced: the Rep here didn't say "there is no 5ed in the works". He said "we announced everything we intended to". Two VERY different things. The fact that there wasn't a cancelled announcement at the last minute doesn't mean that the rumor about 5ed is false.
The problem with statements like "5ed is right around the corner" is that these types of statements are inherently correct and largely meaningless at the same time. "Right around the corner" is vague and everyone has different interpretations of what that means. For some, right around the corner means January. For others, it could mean "within the next 3 years". Both are relatively short time periods depending on how you look at things.
I am sure that they are working on 5ed. This is because the moment the designs for 4ed were finalized (meaning the ruleset, etc.) WotC employees no doubt started at least
thinking about what changes they would like to see made for the next edition. I am sure the design decisions for 4ed were not unanimous after all. When an R&D guy though starts thinking about the next edition, he is inherently working on said next edition. Combine that with the fact that a 5ed is almost inevitable as it increases profits with new book sales (at least in a short term) and its easy to say "they are working on 5th Ed."
Thing is though, you have to then take what Mearls said at the product announcement seminar. He remarked specifically about the way in which 4ed was handled with its announcement and how they don't want to repeat that mistake. I was at GenCon when they announced 4th Ed. (not at the seminar but in the Sagamore right after it) and the only thing that saved WotC (from what I saw) was the excitement over the digital tools. The general reaction to a new edition though was far from positive. Well, they can't rely on the digital tools for their 5th Ed. Announcement.
So, we can assume that they won't try to mislead us (per their words) and spring it on us as a surprise. Lets combine that with their history of a) preferring to announce it at a major convention, b) preferring to have several months of advanced previews of the new system prior to release and c) preferring to have the new system out at least a couple months before Gen Con so that players can be familiar with the system, and you have a recipe that largely suggests a Gen Con announcement. This is the main reason why I say it will be 2013 at the earliest that we see 5ed. (realizing of course that this is all speculation).
So [MENTION=91812]ForeverSlayer[/MENTION]: perhaps you can assuage some of the back and forth here by clarifying what you mean by "around the corner". If your definition puts 2013 within that time frame I think a lot more people would be on board. To me personally (and again this is just my personal opinion) "around the corner" would mean within the next year.