Flew the same route as OP, and my experience was very similar to OP.
Food - 4 people travelling together and we got 2 different kinds of food - it was so salty. On the way out 1 drink was offered but not on the way back.
Seat - I sat right in front of the loo at the back of the plane from IAD-CPH. I got woken up whenever someone flushes the toilet. Then the light at the galley was on the whole time, and the crews were chit chatting all the time - again couldn't sleep well because of that.
IFE - my kids complained about it like crazy because they can't pause a movie. I gave up using it.
2 months later we were on TATL with UA (777-200 from LHR to LAX), wow that was a huge difference - as UA S we were seating at Y+ without having to pay. Food was ok but the crews were much nicer and walking around constantly to serve drinks. The IFE - well it doesn't take much to beat SAS's. Then we flew AC back from YYZ - once again it's better than SAS - nice crew, ok food - at least you have a choice (except the oven was broken so they couldn't heat up all the food at the same time).
I don't even want to compare SK with TK. Why am I flying with them? It's because they are cheap (DKK 2000 to DC, DKK 4500 to PVG during week 44), since we have lounge access then we don't have to be dependent on their food and drink. I don't care about the IFE since I'll be sleeping anyway. 100% miles is another plus too.
I doubt that SAS is going to any positive change - the 'new' Y cabin would probably be LH's NEK which is total rubbish IMO - paper thin seats that will automatically recline when a pax weighs over 80kg.