People need to forget about Nokia and Jolla joining forces. First of all, other than a brand, Nokia have nothing that Jolla need.
The second thing that makes collaboration difficult is the fact that Nokia and Jolla have now become competitors. Both are selling a very similarly specced tablet at around the same time at the same price point.
I think a more likely scenario over the next year would be for Jolla to collaborate with the likes of Meizu, Xiaomi or one of the Indian mobile companies to have them make a device that runs Sailfish.