I can see how airline buyers might want to buy wine now for future use in 10 years time, and hope that it appreciates on the secondary market thus giving them a paper saving, but more and more the estates that sell en primeur (i.e. Bordeaux) are pricing higher to take advantage of that future appreciation, so the cost advantage is disappearing (just compare 2006 - an average vintage - en primeur prices to 2005 - a superb vintage). Secondly, the storage costs of wine (if you're doing it properly) are not insignificant, particularly on the scale that the airlines would need.