Well, only time and data will tell, but the idea of entry level lounge access suddenly becoming a motivator for paying hundreds more for J over Y (which often won't even be available on the return leg from a lot of airports) doesn't sound like a mass market proposition.

Especially for lapsed Silvers, many of whom will be all too aware how mediocre said lounges can often be.

And then also factoring in the proportionally higher seat selection costs when you no longer have status...

Nor do I see large companies suddenly allowing their employees to book J out of sympathy for their lost status, and we know from previous threads that it's often tricky/frowned on/impossible for employees to self upgrade in those circumstances, even if they were minded to do so.

So while I'm not saying no one is going to do it, I do really think this is edge case stuff rather than a needle moving data point. The hundreds that one might spend on a single flight to upgrade could be much better used invested in an Amex platinum, Priority Pass, or similar, which would get you a whole year of benefits.