Has there ever been an Lego Ideas set that made it into its own theme, let alone bring back an old theme? I don't think so. Because the fact is that these sets are mainly for collectors, and the sets are also quite expensive which means that only a small amount of them will be sold. In other words, even if there comes a Bionicle set from Lego Ideas, it won't bring back the entire line.
What you're hoping for is just unrealistic. The glory days of Bionicle are long gone and will not come again.
funny thing is, if bionicle did come back, and had the same universe as HF, and was popular once again, Lenny would be laughing at us.