Manx's, AJS, Gilera and a few others have been replicated, there are all sorts of arguments for and against replicas, in the case of Manx Nortons the replicas do all the winning because they are pretty well re engineered in the process of being replicated, however, the number of original bikes that people are 'prepared' to race is shrinking as they gain in value, the replicas bought a lot more competitors.
Not everyone is like Dave and prepared to race the hell out of their RN400, most likely it will end up in a 'collection' some place given its value.