Alternate ALT… anyone know/have heard anything about the odds of being upgraded?

Hi everyone. Firstly, congratulations to everyone who has been shortlisted!! And good luck to everyone still waiting on their results.

I just got my email from JET, and I was offered an alternate position for ALT. Just based on my own internet searches, I read that many/most alternates (70-75%) do get upgraded since 20-30% of shortlisted candidates drop their position. And that who gets upgraded depends on how high up on the "priority" or ranking list the alternate is.

Does anyone know how true this is? Or how likely someone is to get upgraded? Thanks so much.