Interesting thread. I have a similar issue with how many people are seeing the game and going "LOL KFP!", but even I have to admit that Blizzard is not helping the situation. One look at the racials they chose for the Pandaren even made me think "Po", like the Bouncy and various eating and cooking racials. If Blizzard did some light changes to the aesthetic and racials, many people wouldn't be jumping on the similarity. Like Dave implied, many of the players in WoW, this will be the first time they see the Pandaren other then the little pet monk.
When it comes to the difficulty argument. Let me be straight here based on what I know. The exodus of players we saw in Cataclysm was not hardcore players that would be in raids. Cataclysm, by the standards set in WOTLK, was more difficult and required more effort to move into the endgame. Mike Morhaime admitted to the fans that they made the entry level of Cataclysm overly difficult, which caused players to log on without any idea what they wanted to do because they didn't want to throw themselves at dungeons due to high chances of wiping. The lack of decent dailies until Molten Front was added didn't help matters. You may not notice these issues now, as they have lowered the difficulty and new forms of gear are becoming open, but it was a big issue at release, when Blizzard saw the highest amount of casual unsubscribes.
They want to bring back those casual players, thus why they are massively increasing the end-game progression options in MoP. You can now get "gear points" from dungeons, raids, and dailies. They are adding a Raid Finder that will allow you to queue up for raid battles at a level easier then the normal raids and cut into shorter durations. You will have pet battles or scenarios. They will still obviously have PVP options, and are even promoting a bit of World PVP on Pandaria. For instance, we will have a new "Dalaran" like city on the isle, but each faction will have his own, and they will not be marked as santuaries. They are going to want players sieging the enemies city, though they will add options for players that don't want to take part to escape (portals to other, safer cities, for instance). They are also adjusting resilience, so that players have an easier time getting into the fights before they stack up on it.
When it comes to those hardcore players, Blizzard is not trying to throw them out in the cold, and I think will actually be pushing for them to have even greater challenges. First, with the Raid Finder around for the casuals, this means Blizzard can boost the normal and heroic variations of raids and never have to "nerf" them. Second, they are experimenting with Dungeon Challenges. These are dungeon runs where you have your stats normalized, and thus will be very difficult. As reward though, you will gain items and things that are unique for transmogrification, meaning unique looks that you earn. They can easily extend this in the future to raiding groups, maybe even a new form of heroic.
I always split the "casual" and "hardcore" down to two major things. Casuals want a constant sense of progression and choice in what to do. They don't like "cockblocks" due to difficulty. Hardcores on the other hand never seem to actually want a challenge for challenge itself, but because they like being exclusive, they like having those bragging rights of saying they were one of a few that took down such and such boss. It is hard to balance because you have to make the dungeons open to casuals otherwise you form that cockblock, but the more open you make it the less exclusive the hardcore players feel. Can it be balanced? I think so. I actually propose that every raid have a "heroic-only" boss similar to Algalon or Sinestra, something only the hardcore can fight, and hopefully, gain unique items that wouldn't drop in the normal raid. As a casual I would be more then willing to give up some end game bosses as long as the majority feel open to me.
After Cataclysm, I am overall weary and am going to be a bit more reserved. I don't think Cataclysm was a horrible expansion, but as a casual player it destroyed many of my progressive paths and made things I enjoyed a bit more clunky (no easy casual guilds). I ended up finding myself only running battlegrounds because it was the only place I could level, get consistent progression, and always know I was working towards some decent items. Dungeons were to much of a roll of the dice, because if it failed and ended, I got nothing from it.