When does Sion's rework hit live?

I'm calling a week or so. Preseason 5, after Worlds finish.

next patch which was supposed to hit today if there weren't any delays. obviously there was a delay

They never made a patch maintenance announcement so anyone who says it was supposed to be today does not know that.

Chances are it will be soon but there were a few PBE patches today containing bug fixes so I'd assume the PMA is going to be very soon, probably tomorrow and the actual patch usually hits 24-48 hours after the announcement.