I think Pokemon knows what they are doing here. Sneaking a clip of a new Pokemon in with the last Pokemon Direct, leaking a video. Is it possible that this was an intentional leak? Look at them sneaking Professor Oak in there with the "XY1012" screen. They know that we'll stop the video and look these things up from watching the fans react over many years.
"It must be really exhilarating for those people who enjoyed Pokemon Red and Blue" - Satoru Iwata, Pokemon Direct 9.4.13
Pokemon knows that with the Megas, Kanto starters, and a lot of other things they are bringing both their older and younger fanbase together very well with X/Y. A lot of my friends who haven't played Pokemon in years are suddenly interested again. The reinstatement of the "Gotta catch 'em all" motto and references to the first seasons of Pokemon are probably to bring back a sense of familiarity to fans who may have left the series for many years/bring back memories from the older fans. Additionally, this will introduce "Gotta catch 'em all" to a new generation of Pokemon fans. It's seems almost like a call to arms - "Be ready to catch a ton of Pokemon, fans!". I wonder if there will be an obscene amount, including all of these Megas...? They could be adding a lot this time! Ishihara said in the last Pokemon Direct, "As a player, it's fun to imagine how each Pokemon will turn out with Mega evolution. I want to see what happens to every single Pokemon." Hmm... how will this tie in with "Gotta catch 'em all"?