How many ninningers are there going to be since starninger is appearing early, does this mean there might be more than six?

I think there could be. I wouldn't mind seven Ninningers, but the seventh won't debut until the fourth quarter (when the catalogue comes out)

What if we have a technological sentai powered by mystical stones ?

I think that those two facts would contradict each other. They would no longer be tech-based if they were powered by magic.

So like Zeo then?

Ohranger! This is the Sentai-Thread, after all!

And Goggle V I guess

its safe to assume
that there will be a 7th ranger and he might be an anti hero for all we know
kinda like what happened with magirangers
"we got a load of hints about that series"
he might pop up at EP17 or 18
or 20s

or who know's starninger might officially join the team in episode 17/18 sh
just to stay to the 6th sentai theme brand

Ninjaman
 

cuz he's effin rad that's why

What if we have a sentai could be powered by rings ?