I think it safe to say that Gene Roddenbery had always intended for the Romulans to end up the way they did from TNG onwards. budget and make up from that time made it difficult. It could be argued that the ridged Romulans were considered a minority they were frowned on by pure vulcan descentands Romulans majority (Those who hadn't breeded with the Remans and were frowned by pure Remans were miners) between TOS(where pure Romulans were in charge and the interbreeds were the workers) to TNG (Where the interbreds were in control and the pure Romulans were in the minority) The Romulans are always in a state of Flux. after the Dominion war where the whole quadrant was still in chaos. Shizon saw hus chance and toke it.