The 40K is to reach Diamond level in Asiana Club, which is the equivalent to *A Gold. If you did 40K in the first year of the 2-year qualifying period you'd end up with 3 years of *A Gold. If you take the entire 2-year qualifying period to reach 40K, then you'll only get 2 years of *A Gold. But this only goes into effect starting Oct. 1. Before that any miles earned will fall under the old rules.

Another option in that area is bmi's Diamond Club (not "Blue Diamond;" "Blue" is their term for entry-level membership with no status). It takes 57K status ("membership") miles to reach DC Gold, which is also *A Gold, but only 38K per year after that. What's more, you don't have to fly the whole 57K in one year. The first 3K get you Blue+. At that point you start another year in which 16K get you Silver. You then start another calendar, hopefully your final one, in which 38K gets you Gold. Some fares, obviously not the cheapest but some of them in economy class, count 1.5-3x toward these. More details in the bmi DC forum, of course.

BMI and Asiana look like great options within *A for those looking primarily for lounge access. The rules for achieving the level equivalent to *Gold are a bit more complex than for the North American airlines, but it'd be worthwhile for the OP to carefully read the rules for all of AC, BD and OZ, and consider his (or her) flying patterns before choosing one. If you can flying the carrier's own metal for at least some of the flights, you may also be able to take advantage of some upgrades.

Or you can skip the Blue-to-Blue+ level and go straight to Blue Plus, using this link. It'll also give you 4,500 destination miles (along with the 3,000 status miles needed to get to Blue Plus).

I can vouch for the Diamond Club being one of the best out there - especially for someone who may not be flying all that much. DC has a reputation for being very generous with destination miles - lots of free promotions, plus they let you purchase awards using cash and miles (At a rate much more favourable than buying the miles from BMI). I was able to book SQ F HKG - SIN - LHR - CPH for £170 (plus taxes), without ever having credited any *A flight, or taken out a DC credit card. All just promotions and surveys over a four month period!

One problem with BMI's program, as far as the OP is concerned, is that it has poor earn ratios on Lufthansa's cheap to mid-priced economy fares. Only Y and B fares earn 100% miles. Lower fares earn only 50%.