The 747 in it's various forms has been on life support since 2001 when Airbus pulled the plug.
I suppose you mean 1991 ?
That was the first flight of the A340, and after that date there were practically no more orders for the 747-400. Most airlines bought it for range, not for capacity, and once that range was available at much lower cost and lower capacity, the end of the Jumbo had come. Just like the availability of the long range 777 versions (together with the ETOPS regulations) killed the A340, when all of a sudden you did neither need the capacity nor the number of engines to do the range...
Funny that expectatios have shifted so much. Boeing once predicted the total number of 747 to be built far below the number of A380 already delivered by know. How luckily wrong they have been... Compared to Aircraft like the A310, L1011 or DC-10 the total number of A380 built will be absolutely fine. Businesspeople believe they can sell as many A380s as they have sold A320s. They never will, the market is totally different. The market for high capacity long range aircraft is limited, has always been limited and will be forever. There ist not enough market for several types of such aircraft. Now the much older 747 will die first, and still be remembered as one of the greatest and most succesful aircraft ever.