Yes, the cheshire cat said "we can't go home" but he didn't mean Wonderland, he meant the real world. Because the player is expecting Alice to walk out into real London, cured of her psychological problems.
And that's the symbolism between the blend of the real world and Wonderland - that Alice is not fully cured.
Moving on, the very final scene of the game shows "The Looking Glass"
This pretty says there will be Alice 3. If anyone has read the book, "Beyond the Looking Glass and what Alice found there" is like a continuation to the first book "Alice's Adventures in Wonderland".
McGee did the same, he gave us a glimpse into the Looking Glass.
Furthermore, the cat says "Our Wonderland, although damaged, is safe in memory. . . . for now"
So if McGee decides to get on that, we know what to look forward to from Alice 3.
I just hope they ramp up the graphics and that they don't take a decade to make another video game, lol