Originally Posted by
johnden
What bucket/criteria are used for making paid upgrades available?....
it depends, there appear to be multiple programs and its essentially impossible to tell in advance which program is being.
In some case you will be provide an opportunity to see the new fare rules but in cases where R is used you will not.
Originally Posted by
johnden
....Can this be an elite-friendly gesture? Offering the seats to those with UA miles to spend or upgrade instruments to burn instead of offering the general public a discounted BF seat?
Hard to tell, but most indications is the offers appear to be independent of being waitlisted or having miles.