The only certainty is that none of us no what the hell we are talking about. If 1+ year ago someone had mentioned that the 1DsIII and 1DIV would merge into a 1DX, that person would have been called an idiot and flamed beyond belief. The armchair Canon executives can speculate all they want on what Canon will or won't do, but no one really knows. We can hope and dream, but that's it.
No, Canon publicly announced a long time ago that the 1Ds and 1D lines would merge.
I at least have been expecting it and I'm not surprised. The only thing that I wasn't expecting was the name change, but really that's nothing.
p.s no != know.