UPDATED 7/2/12 6PM EST
Saban Brands has stated after the International Licensing Expo 2012 that they are contractually obligated by Toei to not skip a Sentai season.
Here is a question that is asked a lot but I don't think it has been highly investigated. The question I am referring to is the fact that so far (as of 2011) Power Rangers has been adapted from every consecutive Super Sentai series since 1992. No series after Zyuranger (1992) has been skipped for footage. They may have skipped suits like Dairanger but they used the footage for zords, some arsenal, and monsters so I still consider it using a consecutive Sentai series, same goes for Season 3 and Kakuranger. They didn't skip a consecutive season because if they did, we wouldn't had Thunderzords or Ninja Zords. Adapting for me is using any amount and size of footage. In the credits for Season 2, they mention Dai Rangers and end of season 3 they mention Kakuranger, very little Zyuranger footage was ever really used by season 3. So the question is if Saban (and Disney when they owned the franchise) contractually obligated to do the Super Sentai series in order and not skip one? Linkara has brought this up in History of Power Rangers, he felt like Carranger could be skipped. Many people have wished many a Super Sentai series would be skipped, many even thought Shinkenger was 'unadaptable' and now we have Kanji at McDonalds. Linkara also brought up the topic of the possibility of using a Super Sentai series prior to Zyuranger. Many fans had brought up in the past that a past Sentai could be adapted. I agree that could have. I would had welcomed to skip a series as well.
So far it is an unspoken rule to not skip one. I think it goes higher than Saban or Disney, I think Bandai is also in the works. Many people think Toei doesn't play into a lot of Power Rangers but I think Toei is more in control. Because Toei recently approved that Power Rangers Mystic Force to be an online game for South Korea. Also Toei lets Sentai be labeled as Power Rangers in Korea and Thailand, so maybe Toei has more sway. Also at the end of Mighty Morphin Power Rangers Movie, (which I've seen so many times lately because of my nephew) it says A Saban Entertainment/Toei Company production. Anyway, there is no official statement that we know of that a Sentai series can't be skipped for Power Rangers. But I, myself, with no confirmation believe that they can't skip a Sentai series. Maybe there is a contract and maybe not, but since no series has been skipped, makes me think there is a contract or an unspoken agreement. Also fiscally it is bad financial move, here are cons and pros. The reason there is more cons and than pros is that some cons are to adapt or not adapt.