I'm willing to bet the behavior changes resulting from any reduction in SL lounge access are not going to be nearly as great as this thread would have you believe.

If you're a SL routinely flying in J, you're not affected by any reduction in lounge access as a SL benefit.

If you're a SL routinely flying in Y, where else are you going to go? No other program is going to give you lounge access at that level, either. If you're a hub captive to CX, no other oneworld program is going to earn you miles on most discounted fares. And pace those saying they'd switch to AA nonstops to China, CX is banking on you preferring frequency and better customer service all around when push comes to shove, and they're not wrong about that for many pax.

If you're a hub-captive SL who always flies PEY, CX still isn't worried about you. Maybe you book on BA or QF if those options suit, but otherwise you'll continue flying CX but will bank the miles elsewhere, leaving some other carrier to deal with the cost of reimbursing carriers for your reward travel.