Bumping this with a question as I just noticed they were doing this on LAX-SCL.

Does anyone know with some degree of certainty what the cabin layouts of these two planes are? I have J tickets booked via an Alaska partner award for late January, with a return in mid-February on LAX-SCL. The 787-8 has 30 J seats. These planes appear to have fewer seats, which would mean there appears to be a risk of an invol downgrade to Y. I am going to guess that, despite booking 330 days out.... award tickets like these would be first on the chopping block.

LA is still advertising this route as a 787-800 and showing the full 30 seat J cabin on their website.