With Crossover Rewards for Delta, SPG have given US flyers a great option and opportunity to earn extra points for spend they would have made anyway. It doesn't help those who aren't loyal to DL, but at least the opportunity is present. Partnering with Emirates gives those in the Middle East a viable option to do the same.

However, those living in Europe are a bit stuck: unless willing to split loyalty between Delta for west-bound travel, and Emirates for east-bound, it's not clear who they can fly with to attain the same benefits.

Would SPG ever consider partnering with a European airline - or would that present too much direct competition for its existing partners? It seems to be that it's about time: SPG has a fairly large European customer base and I can't imagine many of those would naturally choose to split their travel between Emirates and Delta!