I think it'll happen, but be limited. Essentially I don't think JPJ wants to tour. Pagey obviously does. And I don't see Jason Bonham having a problem, since all he ever seems to do is play touring muscian. Percy tours himself anyway, so I doubt he'd complain at the money.
I think it'll happen, but it'll be four or five massive shows in England (Wembley Stadium, Millennium Stadium etc), key cities in the US like New York, LA etc. and perhaps some big Euro places like Berlin, Copenhagen, Stockholm, Prague etc.
I had actually heard they're already scheduling a date in Dublin.
Whatever happens, it's not going to be extensive.
10/12 Black Sabbath
18/12 Black Sabbath