They started blasting the pit well before Nemesis was on the drawing board, it was already a big hole by 1991, hence the rocks from the pit being used for Katanga Canyon in 1992. It was blasted for Secret weapon 1&2, the pipeline coaster that was never to be. So it wasn't actually 'designed specifically for Nemesis.' In fact Nemesis was designed specifically for the pit.As others have said, the Nemesis pit is designed specifically for Nemesis.
With that in mind, it is clearly not unreasonable to suggest a good replacement for Nemesis could be found to 'fit the pit.' However I agree, this is very unlikely, and would make very little sense, when you have a 'world top 50 coaster' sat there that just needs some TLC.