Fiveman's toys did not sell gangbusters.
The gender-specific henshin roleplay toys did not do well and the Magma Base, which was a fresh concept when Turboranger did it with the Turbo Builder, hardly sold(also Turbo Builder was 12800 Yen while Magma base was 16800 Yen) thus resulting in one of the worst toy sales for Bandai(while on the same year Winspector was printing money for Bandai).

And while the show was not that bad, the merch had bits and pieces of mannerism seeping out.
Five Robo is a generic mid 80s sentai robot, Star Carry/Star Five is pretty much a design recycle of the Tank Command from Flashman.
Super Five Robo and Magma Base are just recycled versions of the Super Turbo Robo and Turbo Builder from Turboranger.

Ah, I see, then.
Strange, but I guess it makes sense. I can also totally see Magma Base not selling.

It does make me wonder if carriers ever sell well, though...

Eh, you never know with these things.
If it looks cool and plays well as a toy probably. And reasonably priced. :)

What's kind of sentai Theme we can expect in 2017 ?

Well, considering how there's no rhyme or reason to them, who knows.

Gashapon machines and capsule toys.
Each capsule toys will contain some kind of monster, and each ranger will have a "Main" capsule monster that they, perhaps, keep in their pocket, to morph with.

Interesting. And for some reason KR Birth comes to mind.

If JAKQ and Blade can both exist, then Birth and this idea can both exist.

You do know why I said Birth right? And that is very true.

Yes, I do.
I'm just really used to everyone pointing to a KR series going "They did it, so Sentai can't" when people think up ideas for Sentai :lol