When I was consolidating a few years ago, I wasn't totally sure where my new home would be, but I knew it would no longer be DL, where I was Silver Medallian. I went to US, CO, UA and AA to see if they would match my level. US, CO and UA did so immediately with a copy of my statement from DL. AA issued me a challenge --- i.e. if I were to fly so many miles in so many months, then they would match it. Needless to say when I settled on AA, the others did not renew when my mileage on them wasn't significant.