What change do you want to see on your main class for Endwalker ?

[remiff]

It would make more sense if it was a Worm Trance -> Demi-Shinryu instead, since Diabolos wasn't a Primal.
That said, and considering what we've pulled off in the Eden raids, it would be theoretically possible to create a Diabolos Primal (based on the voidsent one) from which we could create a Trance/Demi-Summon out of.

Other than that, I agree with your list.

I know the chances of see diabolos are pretty much improbable, but as it is a summon in other final fantasy games so we never know .

Demi-shinryu is more than likely, but it would probably be too similar to bahamut.
on the other hand if ever one day they come out of glam for the demi-primal why not.