Good Afternoon

I still see a lot of DC-8 and was wondering much long are they going to last? The last DC-8 was built in 1972 that's over 30 years. Could they last till 2020 or are they on there last legs. I have recent grown to like the DC-8 because was Douglas first jetliner and I hope they stay around like the B-52 and KC-135 and not go the way of the 880,990 or 707.