Gr8, yes and no. Flying Blue counted all partner airline and alliance flights until very recently - i.e. the introduction of UXP's which was in the last 20 months or so. United and American also counted a far greater amount of partner airlines until just a few minutes ago (and for that matter until not that long ago AA even counted your Credit card earned miles and pretty much everything else.) BA counts the miles that you have taken on almost any other airline, but has pretty much had the caveat for many years that one must fly at least 4 BA segments per year to maintain status. As you say, DL counts them, but keep in mind thatstarting about 4 years ago, Delta has severely curtailed the ability to earn status miles on many partners including ST partners. So while you earn status points on AF/KL/VS at the same rate as Delta, on other carriers you earn half the amount or less, and on yet others, you earn NONE. SQ has always been SQ, and has been extremely restrictive. Asiana counts all miles BUT you have to also have 1000 flights with Asiana (they are 100000 miles AND 1000 flights). I believe that VS allows Delta and FB miles to count. So it is not all that cut and dry.
Avid, I do not think that there would be any tiers in this, I think it would be Elite for a million and no EP, so that it gives people a reason to keep flying. But also be careful what you wish for as the introduction of such a MM program could also come with the increase in levels to earn status, and perhaps the shortening of their year to each year, much like LH. You think that if they are going to react to this competition, they are not going to follow/copy the competition?