This article (from which the above graph is taken) summarizes a couple of others saying the same thing: we're already on a nearly-sustainable trajectory toward fiscal sanity.
I admit I'm not enough of a student of the finer points of economics to judge all this. But I like graphs, and this one seems more encouraging than one might assume from the rhetoric coming from the teabagging zones of D.C.
See the orange line in the image? That shows the debt trajectory under the status quo -- which includes the Budget Control Act approved in 2011 and the American Taxpayer Relief Act (the bipartisan Biden/McConnell fiscal deal) signed into law last week. Under this scenario, the debt, as a percentage of the economy, will dip through the end of the decade before climbing again.
Which is why that red line in the image is interesting.
As the CBPP sees it, if policymakers agreed to about $1.4 trillion in additional debt reduction, the country would be on a "sustainable path." This does not, to answer your next question, include the sequestration savings, which are due to kick in next month.
In other words, for all the handwringing, if policymakers can agree to a balanced deal to replace the sequester sometime over the next seven weeks, they'll practically be done with debt reduction for a long time.