Although I guess if the "Zords" were based on sailing ships, that would be a change of pace from the usual cycle of animals, cars, and animal-cars.
And they can turn into past Sentai heroes? I.e. recycle costumes from old seasons? I guess that's the anniversary theme... but it also kind of fits the pirate theme, in the sense that they're "stealing" others' identities.
As for Samurai, are they bringing back the old MMPR theme (which I never much liked), or is that just for the promo?
The pirates theme was primarily chosen for the rise in popularity(One Piece, POTC)
The mecha rumors
GoukaiGalleon (Pirate Ship, Red), Airplane, A Car, Submarine, Trailer.
Future mechs will have relations to other sentai, such as Wizards, Detectives, Samurai and beyond.
What it sounds like to me is auxiliary mecha will be designed to pay homage to different themes
There could be dino aux headders, ninja headders etc etc.
The headder concept is basically smaller auxiliary mecha/toys that attach to points on the robo
The current series Goseiger started the concept
Here is how they're used for toys. Goseiger had three sets representing Sky, land and sea
Here's how they're used on the show
GoseiGreat for this year's series which will end in February
The Goukaiger robo will wear different headders for attacks
The Power Ranger theme in the Samurai promo was purely for nostalic reasons