I understand that all the changes will go into effect when there is one system to deal with. Though some seem easier than others to do at that point. Mileage bonus changes and upgrade windows for example, seem like they could probably easily be implemented, for say, flights being on March XX, 2012. But when you're talking about losing access to free E+ seating, and perhaps free baggage allowances, how will this be implemented?

For example, say the one new system goes into effect on March 5, but a 2P books a flight with an E+ seat on Feb. 25, for an April 1 departure. Will they be able to keep that seat based on selecting it before the change actually went into effect? And will the bag allowance be grandfathered in for the itin, as other baggage fees for GM's have been?

I'm about 90% sure I'll hit 1P (or whatever the new short form for gold will be) this year (and based on the differences, will definitely strive for this, even if it means my first MR), but my SO will still be a 2P.