From the article:
"Should airline fundamentals deteriorate, we believe the stronger carrier would likely wait for a bankruptcy scenario to acquire the other," Keay said
I think this will be the most likely scenario. Again, it's just an opinion on my part, but CAL is in a much better financial position than UA, why would they merge with a company with such level of liability, when they can just as easily wait 'til UA goes into chapter 11 protection and align their cost structure with CAL?