Vizards will help SS only if they will not have other choice. When Karakura will be in danger (really danger) they will help, like Shingi helped Ichigo, when he fought Grimmy
They will help whoever is trying to save kakura town. But after they save the town, they may want to have a little chat about thier shinigami status with CC.Also since the Central 46 is no more, they may be able to bargain to get accepted back into SS. But the real world is much better.
I just dont see the Viz's being to grateful to SS for their treatment. Shinji did say he owns Aizen for what he did. He really did inadvertantly make them more powerful. Its gonna be funny to see how this turns out.
They were more of test subjects, not really the end result he was looking for though. They didn't say anything about owing SS, just Urahara and Aizen, if I remember correctly. Urahara saved their lives, Aizen endangered them.
I don't think they will fight both sides. Imo, many of the captains at the time may have sympathized with the vizards' case...it was just that they didn't have any say in the matter.
The vizards are necessarily on the same side as SS, but they both entities share the goal of defeating Aizen.