The fundamental argument if favor of social security reform is that we might not have enough workers paying taxes to cover benefits for future retirees. So, lets only allow people to retire whose retirement we can afford within the social security budget. If the budget is consumed, and you are old and want to retire, you must wait until enough existing retirees kick the bucket to free up the funds to cover everyone up to your place in the queue. If you want a guaranteed retirement date, buy private insurance. Insurance companies know how to manage that sort of risk better than governments.
It would be nice if the government allowed deferred taxes on retirement savings but that is a non-sequitor to the question of whether social security is solvent. The earlier we make this reform, the better existing workers can plan for their retirement.