A "world championship" does not only mean that it has events around the world, but that it also has the best events. While I agree that there might be events worthy of replacing Sardinia, I'd rather have four events (Portugal is not on the Mediterranean, is it?) around that sea than events in India, Korea and who knows where, with all due respect for those countries. If it was for me, Mexico would have been long gone after spectators throwing rocks on cars for a couple of years some time ago, but it was kept because it's in North America...