Hmm, they are still selling Y seats (Y7 - B7). It’s J1 and as per the seat map all J seats are allocated.
So if Y is oversold (which it may be) they’ll have to upgrade J to F.
Not sure how many Plars there will in Y be on that flight, they are the only ones trumping you.
Difficult call. If it was me and I was ‘miles rich’ I would spend them as 16 hours in Y is too awful to contemplate. But on the other hand you have booked it, so you are obviously game for it.

If there are no op upgrades, you probably won’t get a ‘space available’ miles upgrade so you might not even have that choice in reality. So hold out for op up, I guess.
Hope this make sense.....