They may be gone now, but they won't be shelved forever.

From Farsight's Facebook page:

"Official Announcement. (WMS)

Our longstanding licenses for the Williams and Bally pinball trademarks will finally come to an end on June 30th, 2018. Therefore, after this date tables from these manufacturers will no longer be offered for sale within the Pinball Arcade. However, customers who purchased any of these tables prior to the deadline will continue to own them and have access to them within the Pinball Arcade, and we will continue to support them as we do the other tables in our collection. This change will affect all of our devices and platforms.

So if you’ve ever been interested in owning these great tables, please purchase them now, before they disappear!

FarSight will continue to release new tables for the Pinball Arcade. We are excited to announce that Season 8 will launch later this summer and will feature all of the recent Stern tables in Stern Pinball Arcade along with several new tables."

So that's what's going on with this. I know this group has been very inactive as of late, but I thought of getting this out there. If you want those seasons, don't wait until June 30th to get them, and there'll be no discounts either, because of WMS.

EDIT: FAQ on Pinball Arcade Forums:

http://pinballarcadefans.com/showthread.php/13255-Williams-Bally-Table-Announcement-FAQ