Honestly, I never liked the ministry in the slightest, so this is like asking me which arm I prefer cutting off, I'll answer but really I'd just be thinking that I'd rather not.
OK taker needing more power is something that is exclusive to THIS storyline only because he is against kane and the source of their strengths is supernatural, hence why the ministry COULD be involved. But firstly what you would have to do is introduce the ministry, and set any images apart from them being heel, because obvious the ministry was heel and people may still have that image in their head. That initially is not easy.
Moving on, as the ministry in this day and age would only really work either for this storyline because it means something to this storyline, or if taker turned heel you would have to consider turning taker heel again. There are a few problems with this, it is towards the end of his career and I don't think the WWE would let taker go out as a heel and I don't think taker has the mic ability to pull it off adequately anymore. he's not kane, he has never delivered really great stand-out speaking promos like kane has been doing for months now. He honestly couldn't pull off being heel anymore especially since he doesn't look so much like a phenom anymore but a guy with bad knees.
So this would leave you the option of introducing the ministry up until the end of this story.........that could be sunday if taker wins........

If the feud carried on past this sunday then firstly it would be amazing cos its laready gone three PPV's and thats about WWE's current limit for extending storylines, and secondly the same thing would happen, if taker won ministry would have to be heel which I've already explained doesnt really work or they would disband.
Not to mention the logistics or the situation. Here you would have a face stable in the form of the ministry fighting one guy? That doesnt work, you need less numbers on the face or underdog side to draw interest otherwise it would just be the ministry kicking the shit out of kane until the PPV and then the same thing at the PPV.
But you did just give me a brain wave, where I said that kane can carry heel promos and successfully has done this year. This sunday, have it look like undertaker is on the verge of winning, bring the ministry back.......TO KANES SIDE!!!. That would set the feud up for longer and have much more of an impact than simply paul bearer turning once again, bring back the ministry so taker can really fight for survival. I promise you it would draw a far better response than simply taker just winning or the ministry returning to his side, and it would give the guys you mentionned something to do. Btw I agree with all the guys you said, they seem like viable ministry members to me.
So yeah, in unison guys......KANES MINISTRY OF DARKNESS