I don´t think I like that change:

I´m pretty sure FFs will not get free access to premium economy seats, not even on the ridiculously expensive T+ fares.

Now if they take out a few rows of Y and replace them with Y+ that´s great, but that contradicts the "high-density 777" statement.

So this would suggest the number of J seats would be decreased from 42 to 24. In short: The death of any kind of upgrades (and also possibly reasonable Z fares)