I think they would have continued to serve the Shrine for a while at least. Wiegraf may or may not have (SPOILER)eventually become Velius. It's hard to say because although he was (SPOILER)a suitable body for Velius, it was his hatred and desire for revenge that was the catalyst for (SPOILER)his Lucavi transformation. Without that catalyst, it might never have happened.
As for Izlude, I think he would have continued to serve Vormav, obviously; but perhaps he and Meliadoul would have (SPOILER)changed sides upon discovering the truth about their father and his 'friends'... or been killed (SPOILER)by the Lucavi.