Vinnie is wrapped up in a different project. While not officially out of the picture, he's out of the picture. And honestly, he's an average drummer at best.
My hope for Appice only stems from keeping it as close as possible to the Sabbath family, rather than drumming ability. Do you think that as of 2012 his drumming would be any worse than Bill Ward could manage these days?
I think Appice would do his own thing and play just fine. I think Bill Ward would do the right thing, and also play just fine. Something to consider is that Vinnie is content to sit in the background and do nothing more than rudimentary drum work*. Bill Ward played with a great deal of style that actually added to the music. That's something he's still quite capable of, even if he has slowed down a notch. And, last time I saw Ward he really whipped some ass.
Were it me, I think I'd be on the phone with Bobby Rondinelli right now. He recorded an album with Geezer and Iommi, and he plays a better Sabbath style than Appice.
*In fairness, I actually like Vinnie Appice. Much like his brother, he's got a very distinctive, though somewhat limited, style that serves him pretty well in his original composition. I always thought We Rock was an outstanding bit of drumming. His is just a very different approach than Ward's.