Though I think he did say it would appear in a trailer, and this is a demo. But that would be great either way.
A little sad that this (might) mean Wreck it Ralph might not get a full world but this is pretty great either way. I think it would have worked really well to. But I do like that links/summons are not only characters you have met before because it's a good way to include characters that don't have a world. I guess Sora is just that good that he makes connections to people he has not met yet.
This could mean that Wreck it Ralph will be the new world in Union Cross.