This discussion about the mileage in between a qualifying flight and the status activation is interesting.
Let's say I have 3K miles and 2 A3/OA segments (Blue status). I then take an SAS Plus flight, ARN-HKG, which gives me 10K miles and is enough to bump me up to Silver. 3 days later I take the return leg (another 10K) but the Silver status hasn't yet gone through. A couple of days after the return flight, the Silver status earned from ARN-HKG becomes live.
If the system works as nikolask said, then I would be OK - the 10K miles from HKG-ARN would count towards my Gold qualification. However, if the system still works as Knobbgb stated, my 10K miles could go into a black hole and wouldn't count for qualification.
I actually have 6 days between the 2 legs on the HKG flight I've booked so I hope I'll be okay whichever way it works!