Actually reducing the debt is pretty unlikely. However, we could balance the budget, or get close to it, if we were serious about it. That would take changing the tax code, changing the way we pay for entitlements (Medicare, Medicaid, and Social Security), and reducing discretionary spending. We could do all of those things, but neither political party seems to want to. It's easier to buy votes through government spending than it is to win votes with economic theory. And we could balance the budget without a major shock to the economy if we did it through a gradual process that the government committed itself to over a period of years. That, unfortunately, is very unlikely to happen, at least in the short term.
On the taxation side, it's not a huge marginal rate at the top that would likely "fix" things; it's a bunch of smaller, marginal changes. The tax code probably is rather bloated, and does allow property owners to avoid a fair amount of taxation on their wealth. Those things could be fixed, but as with everything else, there's no magic bullet. With entitlements, we could change how the taxation works, removing, or changing the caps on the taxation, and for Medicare and Medicaid, we could probably add additional co-pays (on a means tested basis) that might reduce some of the (legal) waste in the system.
All that said, I think the biggest money sink for us remains poverty. The cost to society of having a significant underclass is very high. Ironically, there's a pretty good body of evidence that shows that being poor is also quite expensive. The societal costs include social spending on what we think of as "welfare," but it also means very expensive school-based programs, crime, medical spending, and a host of other costly ills. That said, the fix isn't obvious, or we would have done it. It is neither cut off all federal (and state) spending and let God sort it out, nor is it give everyone tons of free stuff.
