I don't think A or B would have happened. The Vorta run the Dominion with only very limited influence of the Founders. Look at Weyoun he seemed to handle the war with very little input from the Female Changeling. She seemed fine to let him make decisions and only occasionally got involved. The Founders are the head of the Dominion, but they seem to be a mostly absent one preferring to hide on their secret world. So I question whether if Tain succeeded if it would have any real impact.
The likely outcome would be the upper echelon of Vorta would either conceal the attack. The Jem'Hadar and other Vorta wouldn't believe anything the AQ powers say or any evidence they provide. As someone stated the attack wouldn't kill all the Founders, just those in the Link at the time. A successful attack would result in the few survivors probably taking more extreme actions, particularly against the Cardassians and Romulans. The war that would still come might be more concerned with extermination rather than control.