Some thoughts:
1. The change to the upgrade scheme was inevitable - AA's switch to a 2-cabin model on many longhaul flights means that the airline can no longer treat J as a glorified Economy, and must readjust its business model to get business class fares occupying business class seats. Nearly every other predominantly 2-cabin major longhaul carrier has similarly restrictive upgrade rules - anyone thinking that AA would be any different was out of touch with this industry reality.
2. I fully expect AA to revamp its J cabins within the next 6-12 months. However, it makes good sense from a business standpoint to realign the J cabin revenue stream PRIOR to making the investment in the new product.
3. As is the case with most things, fleeing to UA will only prove to be a temporary reprieve - UA is also planning to rollout a new J cabin (and will probably eliminate F on its 763s as well), and will therefore likely abolish its international upgrade welfare state as well.