I just want to know what will happen to Sora when Ven's heart is set free? Sora is only able to wield the keyblade because Ven's heart is apart of his, but when it's set free and Ven wakes up how will Sora be able to wield the keyblade? I mean Terra chose Riku as the true keyblade master, so i'm just wondering how Sora will be able to wield it when the heart of Ven is set free.
...Wrong. The Keyblade chose Sora itself, and after Riku took it from him, it chose him again because of the light in his heart, and the darkness in Riku's.
Ven has nothing to do with Sora wielding the Keyblade. Now the dual-wielding however, that is because of Ven. He can wield his and Ven's Keyblade.
When Roxas destroyed Xion, he awakened his own dual-wielding, and the two Keyblades(Oathkeeper and Oblivion) took on their forms to symbolize Sora's relationship with Kairi and Riku respectively.
If anything, Sora might lose the ability to dual-wield. But even then, he might still be able to use Roxas' Keyblade as his second one.