1 - The Priest Class Hall tome says it’s a possibility.
There are many theories concerning the blade’s creation. The more outlandish claim that it is all that remains of a forgotten Old God who was consumed by its kin in the early days of the Black Empire. Other theories state that Xal’atath is the claw of Y’Shaarj, ripped from the Old God’s monstrous form and bestowed upon its servants for use in ritual sacrifices.
2 - Xal’atath herself calls the Old Gods her “brethren” and wants payback for what they did to her.
“We may face some of my brethren in this conflict… a prospect that delights me. Their power will be mine! They will pay for what was done to me long ago .”
And the WoW Chronicle art page about Old Gods has five of them.
This map goes against the idea, showing the elements vs old gods and there wasn’t a fifth one here. This 5th old god only ever is seen in the chronicles thing, nowhere else.
If all that was left of her was a claw, why isnt’t she represented as such? She’s shown as a dagger. It could have been “Xalatah, claw of the black empire”.