[Librarian]

A 70s revisit would be interesting.

But as others said, for a kid's show they typically try to skip anything between 1935-1950.

More I'd like to see some more genre era series.
An Edo one is definitely likely for large chunks too. Those sets are always a fave of the crew to do because of many of the movies that inspired them to get into entertainment. But a cyberpunk, or steampunk or similar kind of setting would be extra fun.

Steampunk in particular would be interesting and visually different and it's something we've yet to see Sentai really try. And that could be any era. It'd be one of those alternate world ones like Gaim was.

With the 50th for sentai coming up in a few years, I expect we might see some heavy 70s stuff though at some point. Or at least flashbacks.