I think there are downsides to both. You try something new, you will make the old fags angry. You keep the old, you will make the new fags angry.
It's about both sales, and audience, so if they can keep it balanced, I don't see why worry about the other. If they sell a lot, the show, even with low ratings, can keep going as it was meant to be going. If it's going well with the show, but not selling much, well, they'll do small things, like bonuses, and v-cinemas and stuff like that, I suppose.
I don't really think we should worry about it, as we don't have inside knowledge about anything TOEI does, and believe me, with internet and cable tv uprising in the last few years, audience has a lot more meaning, even if declining. Today's 5% can equal yesterday's 10% in success terms.
Goes for both Sentai and Rider, imho. So I don't mind a great series with stupid gimmicks, or an average series with thousand gimmicks. If they keep trying new stuff, with a nod to the old, I think that's the way to go. That's what makes this FRANCHISE... well, a Legacy. It's been 40 and 35 years by now. And they keep airing. And they're supposed to give the same feel. If they're doing it right... Let them work.