I wouldn't agree with any of these.
Privatization is too risky. People whose whole portfolio was in stocks would be devastated if they had had to retire at the bottom of the recent crash. There would have to be serious oversight to ensure that people were getting out of risky investments as they reached retirement age. That defeats the purpose of privatization.
Means testing would make Soc Sec into a welfare program and there would be much less political support for it.
Elimination of COLA completely would punish those who relied on Soc Sec. Anytime we got real inflation, their ability to support themselves would decrease.