The reality will probably be that the career expecations at both carriers will be similar by the time a merger is announced.
There are always a few that want a windfall from whatever SLI methodology they champion(especially the DOH guys), but for the most part, everyone I speak to would be content with something similar to relative seniority. I know that's too simplistic and not exactlty how it works but in the end that's probably the closest approximation of "fairness".
Anyone who expects something other than relative seniority with slight tweaks is setting up for a big disappointment.
DOH is a nonstarter.