Phase it out:
1) Workers entering the system after the date of enactment of the phase out plan do not participate in the system. They will not have SS deducted and will not receive any benefits upon retirement.
2) Workers currently in the workforce undergo a phased reduction of deductions. They will receive benefits in accordance with their years worked as of the date of enactment of the phase out plan.
3) Retirees as of the date of enactment receive current levels of benefits but there are to be no increases.
4) Phase out to occur over a 20 year period after date of enactment.
5) Etc.
Screw phasing it out. Buy it out. Give the money, in a big fat gummint check, that Social Security-age and near-SS age folks (say, up to age 50) put in, back to them. With interest--but taxable as income (which it would have been if never taken out of people's income to begin with).
Let everyone else out, with no payout at age 62 or 65 or 67. SS is OVER. End payroll taxes for SS purposes.
That is the only way to end Social Security and do so fairly. Taxes would probably have to be increased on everyone to handle that initial payout, but then, SS's final payouts would be taxable as they would be either sitting in bank accounts or pissed away on things that ARE taxed, so maybe not. Seniors take a hit in getting no interest back. Non-seniors don't get any of the stolen money back.
The one piece that is missing and that I assume will quickly become the only real front for the democrats to fight back on this is SS for disabled / children of disabled.
I'm not sure of the details, but social security does pay out to people who become disabled for one reason or another. In my opinion this is a safety net of the program that has value, though not necessarily within the SS program.
I would add to your list the removal of this benifit from the social security program as a whole in place of a very specifically defined and prescribed program which provides the safety net. I see no reason to mix the issues of "retirement pensions" and a real safety net.