Be interesting to see how it works, if it occurs, and whether there is ever any F inventory left.
US top Elite flyers more or less expect upgrades on every flight, so after they are catered for, and get many automatically, and after the United member points upgrades, and money upgrades are processed, will be very interesting to see how many are ever left.
mileageplusupdates.com
There were always big LCD screens at UA gate with a huge list of names who were ''on the upgrade list', and many times that large list
stayed a large list when the flight was closed!
I was a United 1K for 10-15 years, and more or less got upgraded free for 2 million real flight miles globally. Back then you could get upgrades fully confirmed way in advance, on any route globally, on even the very cheapest fares, and in lie flat widebodies all the way.
Cheapie 15,000K flights like SYD-LAX-IAD-EZE/GIG/GRU were covered by a single 1K 'Systemwide' Certificate. All fully confirmable in advance. Those were the days.
Not so easy now for 1Ks -
https://www.flyertalk.com/forum/united-airlines-mileageplus/2060545-frequency-upgrades-1k-3.html
Interesting to see where points upgrades from a non Star Alliance partner will fit in the voodoo upgrade mix now. NC and NF used to be the fare buckets needed. UA must get money for it in some form, so whether they prefer to take Mileage Plus member money, or money from Virgin will be interesting. There is a mega conga line ahead of Virgin members.