I think it won’t be necessarily body parts that become subscription services, though that could happen in the future if organ donations and/or genetic modification became privatised around the world, but I do think that certain implants will phase into human life and become near-essential, and those can be monetised. Like modern day smartphones and computers with all their tracking, subscriptions, and microtransactions, except it’s NFC chips in your hand or brain chips for controlling everyday electronics.