The last SAS DC-9 was finally retired on 7th January this year after more than 70,000 landings. But well, the DC-9 retirement may have dragged somewhat according to plans because of the introduction problems with the 737NG and Dash-8-Q400.
The MD-80s (and -90s) perform very well and are very popular among the pax. So I agree with Yyz717, I wouldn't expect any mass retirement on this side of 2010. Maybe the few MD-90s with the (in SAS fleet rather odd) V2500 engines will go earlier, should a good buyer show up. But the world market for good, used MD-90s sure isn't booming these days.
When the current SAS orders at Airbus have been delivered, and the 767s have been sold, then I guess that the purchacing department at SAS will be rather quiet for some years. There will be a few options at both A and B converted into orders, no more.
Always keep your number of landings equal to your number of take-offs