Merging lists ain't going happen. It's a pipe dream of a small, but vocal, number of KA pilots. Here's a reality check.
There are 3 parties and here's their motivations.
1. For 500 KA pilots this is good news. Lose very little, gain access to ULH rosters and Bases (ha..ha..remember those?)
2. For 2500 CX pilots it's very bad news. The FO looking for a quick upgrade is a bit of a "unicorn". Remember, they are far from a majority and if they wanted the quick upgrade, they would have joined KA in the first place!!
3. The company risks litigation (particularly from the foreign unions under first world labour laws) and a stouch from CX pilots, particularly the Captains, Senior FOs and SOs. (The majority). The company does gain flexibility of crewing particularly on the 330.
As always, the company will be the driver in any decision making process, not the unions. Rather than risk a fight, the company can simply offer CX pilots secondment to KA. The DPA might try and oppose, but they didn't oppose training CX JFOs, so I can't see them opposing secondments. The company get what they want, with none of the associated risks.
Sorry to p!ss on your cornflakes, but that's the reality as I see it.