IMO, if we assume that the Heisei Riders who appeared in the movie were the originals (and the movie supports this to an extent), then the AU Riders never participated in the movie's battle against Daishocker. This would explain their ignorance towards Daishocker in episode 30, and also no longer makes it a contradiction for them to fight one another.
Personally, I'd prefer the TV series ending to be the true finale. Firstly, adult fans like us won't get to see the movie until next year, so if the movie's the finale, we won't get to experience its awesomeness for quite awhile. Secondly, it would be better for the Decade TV series' plot to be contained in itself, with the movie as a nice addition to the overall story, but not necessary to understand the plot. For example, fans who're watching Decade but who won't get to see the movie can just assume Apollo Geist to be the head of Daishocker, and his defeat in 31 to be the end of Daishocker. However, those of us who've seen the movie will be able to fit it into the series by explaining that Daishocker fell in the movie, after the Amazon world episodes, but Apollo Geist was the sole survivor and remained to wreak havoc. Lastly, I find something poetic about Decade going against his destiny as the destroyer in the movie and becoming a savior, only to have to fulfill it in the series. It's a bittersweet way to end the series.