I think the more likely scenario is that the SL in PE would be upgraded to J, rather than the DM from Y who was already upgraded to PE.

I don't have hard facts to quote, but this is based on my experience and observations over the years.

Of course if Y/PE are really oversold so much, it's of course possible that DMs in Y may sit in J (double opup), but I think it's rather unlikely that would happen before all status pax in PE were upgraded first.