Turbo should also be unlocked through gifting subs and/or bits. This would incentivize people to gift to their favorite streamers, and reward members of the community that are generally more active in chats and streams.

As soon as someone gifts 10 subs or 5000 bits, they should get turbo unlocked for 30 days. You can play with the numbers a bit, but that's obviously more revenue than a turbo subscription.