I would assume the current TA would become null and void, (similar to a mariage that gets anulled when it hasent been consumated) (that means, never slept together for the "lay people").
Kinda like never having a combined seniority list, and not flying together.
And on your other point, I dont think you wil find a whole lot of worry over the loss of USAPA anywhere. It will have succeded just fine from theperspective of a majority of Usairways pilots.
Kinda like a great girlfriend, there when you need her to take care of you, but its time to move on to more permanent things....APA comes to mind... )