potential issue for those that will be upgrading a different line

since the new iphone uses the micro sim, what are people planning on doing if your going to use someone elses upgrade and you preorder?

if you preorder, the line thats attached to the upgrade gets connected to the micro-sim. are people going to buy another micro-sim to activate on the line that the iphone is going to be used on but is not getting the official uograde?