I don't think this is correct. I have talked with lots of flight ops personal and none have said this is the companies intent. If they really wanted this they would certainly have asked for it in the two major concessionary contracts or the joint contract completed last spring.
The only reason they converted CVG to the ER was to avoid a massive amount of training that would have been generated had they closed the domestic category outright. The ER category in CVG is viewed as temporary at best. They still staffed it as a domestic not international base for FO's. There are no gains for the company in combining them because the categories are all large enough that reserve and other requirements do not come down. In fact they would end up paying a lot more credit and dropped trips because a joint category can be manipulated by pilots to generate paid trip drops.