Shinkenger did fairly well, yes, but this is being blown out of proportion just a bit. It's not a movie release, but an OVA type thing. It's still very awesome, and shows that Shinkenger is popular, but I think, more so, it shows that Sentai and Rider have gotten increasingly more profittable/popular since Den-O.
How long has it been since a Super Sentai got any sort of post-series continuation or special? I want to say Jetman got an animated OVA, but I can't think of anything else....