I wasn't expecting a resounding 'yes'. I thought the author might be inclined to think that way, based on the last part:

In the meantime, if history is any indication, the political polarization in the U.S. will get worse before it gets any better, and until the country has addressed its underlying economic problems, demagogues and political parties on all sides will continue to look for the issues that most inflame the passions to distract from the system’s failings.

Great Britain was an undisputed global superpower in the last quarter of the 18th century and almost squandered its position through a series of expensive missteps. Though the U.S. eschews the trappings of empire, its global power over its rivals is no less significant than Britain’s was a couple hundred years ago. What’s more, its missteps share striking similarities with those of the British at the end of the 18th century. The most likely scenario is that, like the British Empire before it, the United States muddles through and comes out more powerful than before for a long stretch until it enters a secular decline – all the while believing it is truly exceptional, right up to the very end.

But on second read I'm not sure if he expects the US to get better (short-term more powerful than before?) or not (long term decline).

Personally I tend to eschew fatalism, as it's never very productive. I still believe there are ways out (e.g. Piketty's progressive tax), but I don't think they are anywhere within reach in the current political climate.