Above is merely determination to not give a single inch. Square can change the course of the story however they please. They call those shots, not us. You've gone from "Unrelated" to "Derailment" purely because it involves a self-centered character in your eyes, yet everything he has done has drastic implications for the story and its most relevant plot-points no matter what way you try to spin it. This doesn't become false just because the person in question is in it for themselves.

Everything before ShB hinted at an Empire related followup, as did ShB itself, with Zenos' act now pushing it into an obvious 'chaotic' direction that may yet still force CE's vision to come to pass, just by different hands.

So, let's have a snoop at possibilities.

WoE's (Warriors of Elidibus). New sport? New allies? Enemies of all? Possibly even a partnership, one way or another. Could go numerous ways - WoE's and Zenos, Zenos and WoL, WoL & WoE's, who knows. Might be a free-for-all. Might all be handled separately.
The use of Black Rose by people other than Zenos (Empire, Elidibus). Or possibly himself if pushed.
The inability for the Scion's to defend themselves whilst on the First from, well, anyone. I fully expect at least one Scion to be killed on the Source while we witness their form on the First fade to really push out the feelsbringers.
Elidibus in general doing the whole 7th Doctor 'chess-master' shenanigans from complete safety to orchestrate a Source-nightmare.
Any/All of the above can and will involve the state of the Empire.
Any/All of the above can and will involve Zodiark and Hydalaen, which we're still fresh from.

But sure, X is selfish thus it must be derailment and not advancement.