Aqui,
The reality is that Northwest had the oldest pilot group amongst all the US legacy carriers, so some of your concerns will be alleviated by a disproportionate number of former nwa retirements. Most people held a similar position (percentage-wise) within their respective companies in the overall list.
I really think Delta made out slightly better than nwa in this arrangement. Neither side got what they wanted (the arbitrator stated that this was a marriage of equals, not a takeover) Consider the situation of the nwa 2001 hires, who suffered through through 9-11, bankruptcy and furlough, who now have some mega-junior Feb 08 Delta new hires senior to them.