While I'm happy that Castiel has loyalists...I'm rather unsettled (still) by the suggestion that Cas' Grand Plan involves something so reprehensible that it has his own loyalists turning on him.
My two theories about what Cass is up to...one is the same as before, by other one is new:
a) Cass thinks the only way to defeat Raf and all the other angels who threaten the Winchesters, is for Castiel to become a god/God.
b) Cass is getting foreign help - maybe some soldiers from Brother Wallaby, a few vodyanoi from the gods of the Caucasian Mountains, some soul-collectors from Left Handed Hummingbird, etc.
At this rate, SPN's Castiel is going to make Nikita's Percy look angelic.