As I said before, I wouldn't leave the left hand seat of an Airbus of a very stable (and growing) airline for the bottom of a seniority list with a 15+ year upgrade. I would stay and move to the northern Easy base when seniority permitted. If I were to move, BA would be the only option I might consider given the fleet choice and SH/LH options. It might be difficult to turn down a 787/777 FO slot if offered (you never know what might be available) as I could always return to SH flying if desired...
Regardless, leaving a left hand seat at Easy would be very difficult in this economic climate.