I really wonder how AS and HA will approach the mile transfer issue. On one hand, it's only fair to merge at a 1:1 ratio into AS, for those who earned their HA miles the hard way. On the other hand, there're good reasons that AS isn't any bank's transfer partner, so if the MR-HA-AS route is made possible (even just for a short period of time), lots of people are going to make huge transfers, which very likely would break the current economics of Mileage Plan. Either award availability would be even harder to find or they'd devaluate yet again.

For this reason, I'd definitely wait before accumulating large amount of HA miles, either through HA credit card or MR transfer.