How about heartswap/bodychange?

[Lucid 3]

Well I just had a cool idea .. well at least I think it would be kinda cool !The Idea is that maybe instead of summons or something like this they could give sora the ability to switch to Roxas or Xion !what I mean is .. maybe the two can´t be restored but Sora kinda gets the ability to switch to one of them for a amount of time !like you switch and they kinda switch hearts and with it the body ... for example you play with sora ( normal ) and switch to Roxas ( most likely dual wielding ) or you switch to Xion ( maybe she can partly transform her body to her other forms )Soo it´s very very unlikely to happen ^^but I still wanted to share that idea and hear what you think of it

[Nick Sideris 1,551]

Now that I think about it , it's not such a bad idea . It would make the gameplay better . But ,yeah , I really don't see that happening . And , it's kinda weird , if you think about how Sora can switch to those two .

[Hyper-Rushe 17]

It doesn't make much sense because Sora can literally do everything they can do just better. Roxas and xion until they become their own people they are just cheap imitations.

[Shulk 8,623]

... Am I the only one who thought Pokemon after reading the title? ._.

 

The idea's interesting, but it wouldn't work too well. It'd be kinda awkward having to switch between them, anyway.

[Sorarocks93 678]

What if they could connect this with armors? And basically make them the new limit forms?

 

Ventus, Roxas and Xion are all in Sora's Heart. So when you choose the respective limit form Sora would be covered in Ven's armor with his stance and battlestyle or be covered with Xion's armor (Final Boss of Days) with her own battlestyle and the same thing with Roxas too. Although they would have to create an armor for Roxas, maybe similar to the Nobodies he commanded when he was in Org. XIII?

 

Edit: Basically it's still Sora but with different armors instead of switching bodies completely. 

Edited April 26, 2014 by Sorarocks93

[The Transcendent Key 12,109]

It is an interesting idea, and I agree that it would definitely be awesome if Sora had such a power.  But well, we may never know until Nomura spills the beans on more gameplay elements.