As far as the retirement component of it goes, it's a red herring as our fiscal problems go, changing it is a philosophical or policy issue, not a fiscal imperative. Withholding rates, start ages, and benefit levels can be adjusted to keep it solvent as long as the electorate favors keeping more than not, so the entire topic is just a beartrap for Conservative speakers when it isn't actually what's going to break us.
What IS a problem are the unearned entitlements like SSDI, WIC/foodstamps, direct or indirect effects of social welfare programs generally including Obamacare, institutionalized corruption like green energy contracts, rebates, and credits for campaign bundlers, and failed 'Stimulus' moves that end up costing the taxpayers a million dollars for each $50K job created in the real economy.
There are several problems with means-testing SS retirement, the biggest one I can see is that since it's a contributory system, you would be taking money away from people many years after they put it into the system under specific legal conditions that were supposed to eventually return it to them, which could make it an unconstitutional ex post facto law, since one party is suddenly changing the rules and seizing property of the other many years after the deal was done. It would avoid this problem to some extent if you were to cap the benefits at the total of a beneficiary's contributions (employer and employee) plus accumulated interest at the annual rates applicable to general government obligations over the beneficiary's history, but while not insurmountable in an accounting sense, I pity the fool that would have to explain that one.
