The MD-80/90/95 didn't have a very big order book, and there was no replacement for it. The MD-11 was a failure, and the MD-12 was cancelled. Douglas essentially had no future after 2000. The military side was better, but the A-12 was cancelled, and they lost the JSF. The only bright spot was the Super Hornet, which was supposed to have been an interim aircraft until the JSF started to be produced.
2000 is a bit premature, also in 97, the MD-95 was still a paper aircraft (first flight was not until 1998) - and the last MD-95 rolled out of Long Beach in 2006. Nor was a replacement for the MD-90 obviously needed
The MD-11 had the same issues the 767 had at that time, meaning the market for wide body aircraft was slow, very slow.
I suspect that had the merger with Boeing not happened, the MD-11, MD-90 and MD-95 would have continued on in sales for a while. I'm lead to believe Boeing didn't try as hard to sell the MD-95 (Boeing discontinued the MD-90 entirely because it competed in the same space as the 737) as McDonnell Douglas would have. I also suspect Boeing would rather have cancelled the ship as soon as the merger happened, but it would have cost them more to cancel it then, than it did by waiting 8-odd years.
Growing up in Long Beach, it was clear to all the people who worked at DAC, that Boeing bought them for their Military side, not for the commercial aircraft though.
In the end, 9/11 made the whole new aircraft market go squishy, and it lead to several project ends across the industry - most notably the 757.
In 1997, the 767 had 682 cumulative deliveries, and 120 unfilled orders. The 777 had 104 cumulative deliveries, and 221 unfilled orders. The MD-11 only sold 200 units total in its entire history.
The MD-90 was also non-competitive with the A321 and the 757. You can take a look at the sales numbers. By the mid nineties, Douglas was producing something like 20 a year, Boeing was doing about 50 a year, and Airbus was producing about 25 a year.
Douglas badly needed a cash infusion to get a competitive product flying. Their whole product line was derivatives of 1960s aircraft that weren't even winners in the 60s. Meanwhile, Boeing had introduced the 757, 767, and 777, which were all great aircraft.
