There is no chance. 0%.
I'll explain why for you, and try to clear up the misunderstanding about "other" reverts.
First and foremost, Riot can't make literal reversions to older patches, because they don't have something like a storage of old patches.
https://youtu.be/cV8rhu9mE64 It's stated in this Q&A. They actually do not have that data any more.
The data for old Swain, old Akali, old Taric, etc. etc. don't exist. So it can't be put back into the game. They'd have to recreate the entire champion from scratch.
So, along with that, are the examples of other "reverts", Kog'maw, LeBlanc, and Rengar being chief among them.
But, since those didn't include a change in the mechanical function of the abilities (except Rengar's Q, which I'll explain in a little but), the data was still there. They only had to fool around with the numbers and activation conditions to get them back to how they used to be. But the important thing to remember is that they didn't technically revert anything, they still had to work like they were making new changes.
Rengar's Q was a special case, but since his original Q uses the same animation as his critical strike it didn't require them to add any more animation to put it back. They just had to take away the animation for the new Q.
So can they do a revert? No. They don't have the data. And other reverts you might look to as examples didn't actually require anywhere near the amount of work reverting a full VGU would.