There is very little reason that have to lie about something like this. They've had interviews speaking about when they started projects which are always at the end of the last one they finished. We cannot prove that they didn't plan to have the games release the way they did, nor can we prove that they did plan it that way either.
One interview said they were done with Black and White. It got misinterpreted by the fans so when Junichi Masuda received the comment, it made it sound like Gen 5 was over with B/W which he said it wasn't over, but he couldn't go into detail. When that happened everyone clamored over Grey, which we know now wasn't the game they were working on, and that the original statement that "Black and White's Installment was over" was in fact true.
Unlike with that incident they flat out said, there was no pattern prior to the release of the titles. Which is true no matter how you look at it. Time wise none really match up to the patterns we gave as excuses to push our ideas/theories forward. So far only one possible pattern remains but if the remakes appear in Gen 5 on the DS then that pattern was ruined as well.
If it comes out on the 3DS before or after Gen 6, then there is a possible unplanned pattern still in the run, but release wise, what they work on, and all things pertaining to the next game aren't worked on or thought up until they finish or are at the final stages of their current projects from what I've been able to see based in interviews and reports.
There is no definite hint on what comes next, but like with the possibility of Grey, we just have to wait and see. Gamefreak publicly debunked our theories on release patterns. Really that would be more insulting if they had lied. Then again, maybe they didn't plan any of the releases out and move based on what they wanted to do or thought was more important for them to produce. If the latter is true, then all the fans saying they want something actually means something.
There is very little reasoning as to why they should lie, especially since that specific sentence could have been another I know what I can say, but legally I can't say it so I'll leave this with another political open statement that doesn't answer your question like I typically have to do to cover my own job security. That was one of the rare flat out remarks that actually answered what we asked. There is some credit to it.