Without calling the overall national issue a bubble, it's pretty clear that it's an unsustainable underlying pattern.
To avoid large and unsustainable budget deficits, the nation will ultimately have to choose among higher taxes, modifications to entitlement programs such as Social Security and Medicare, less spending on everything else from education to defense, or some combination of the above.ben bernanke
[There are] signs of froth in some local markets where home prices seem to have risen to unsustainable levels.Alan Greenspan
That said, there can be little doubt that exceptionally low interest rates on ten-year Treasury notes, and hence on home mortgages, have been a major factor in the recent surge of homebuilding and home turnover, and especially in the steep climb in home prices. Although a 'bubble' in home prices for the nation as a whole does not appear likely, there do appear to be, at a minimum, signs of froth in some local markets where home prices seem to have risen to unsustainable levels.Alan Greenspan
Provocatively embedding his argument in examinations of historical power shifts, like those provoked by the unification of Germany in 1871 or the British Empire's adjustment to America circa 1900, Kupchan argues that American preeminence is dangerous to sustain, because it is in fact unsustainable.charles a. kupchan
These movies belonged to the twentieth and early twenty-first centuries that period of great, unsustainable, and hedonistic prosperity, driven by the burning of Earth’s reserves of perishable oil, which culminated in the False Tribulation, and the wars, and the plagues, and the painful dwindling of inflated populations to more reasonable numbers.robert charles wilson
Moonlighting was funny, innovative, genre-busting chaos. Also, apparently, unsustainable. Sigh.jane espenson