Speculate

If X & Y don't have a Breeding Ranch and do not increase the number of Poke'mon you can have in a breeding center I think they will make a new Poke'mon Rancher. It would be cool if they had it on the 3DS and compatabile with the Poke'mon cloud storage system. Chances are they will put it on the Wii and have the Cloud Storage synced with both the Wii & 3DS.

A thought on Poke'mon Z: It seems like they are pushing for the MMO feel with X & Y. What if Z is an MMO and pushes the 3DS to a new level. As far as the game cache & updates all a person would need is a higher gig SD Card with probably a minimum of 16 gig required. It could be done. One thing I am not sure about is how advanced of a server they would need. The fact that it is 3D alone is enough to put strain on a server guaranteed. On the flipside the graphics are still "handheld device" in size and the world itself would not be that big. They could even start you off in one region with every other region programmed in the cartridge but locked until they release dlc or a code for each region. Cloud Storage of pkmn is the only way they could do pkmn storage. The memory required for 10 trainers pkmn in game would be insane after a while. But with all that, pkmn has never made story objectives with an mmo feel at all... ever.

That leaves having trainers in a sort of Social pvp Server. Imagine they create an "island" where trainers gather to battle, trade, play underground base games(maybe), poke'athalon, fashion contests, chat, etc. etc.