Your estimates are greatly inflated, but your reasoning is correct. Expanded Medicaid is the biggest problem, as most of those receiving it are voters.
What about leaving the expanded Medicaid program and terminating the rest of Obamacare?
No, I don't like it, but at least the expanded Medicaid program was optional for the states. The rest of the Obamacare law is what forced the rest of us to give up our doctors, hospitals and health insurance plans that we wanted to keep so we can pay ridiculously high premiums and deductibles for polices that cover sex change surgery.