My gut reaction is to agree with the article: the USSR collapsed from a failure of will. (I'd also argue it was created by an act of will, but that's probably by a subject for another thread.) I don't think deterministic (e.g. economic) arguments are very plausible for explaining the timing of revolutions - the great revolutions of the past, if anything, often happened when economies were starting to improve and so expectations and energies were rising, rather than at their nadir when people were too focussed on economic survival to revolt. Nor should economic factors be relied on to explain the timing of the collapse of regimes - whether in the USSR, in Tunisia or Egypt. There is obviously a connection between economic stagnation or decline and regime change. But it's not mechanistic or exact.

A comparison with China is very interesting. You could say that both the Chinese and Soviet leaderships by the late 1980s were analogous with Popes questioning the existence of God - they no longer believed in the Marxist-Leninist theory that provided the legitimacy for their rule. But in China, the leadership still had the will to impose their authority by force. In the USSR, it did not.

The attitude of the military is also interesting. The Chinese army was probably more content with the status quo, as it was enjoying some of the fruits of China's growth (running its own enterprises). Whereas, the Soviet army was suffering from the USSRs stagnation and relative decline. So economics may again have played a role, but not necessarily a decisive one. In both cases, you could say the military ultimately followed the political leadership (the PLA fired on the students; the Red Army did not stand by the coup).

And of course, Yeltsin played a pivotal role. Once the coup had failed, he could have ushered back in the reforming USSR of Gorbachev. Instead, he smashed it. The flipside of saying the Soviet Union collapsed due to a lack of will is to say Yeltsin broke it by an act of will. I think many Chinese looked at the immediate consequences and did not like what they saw. If Russia's economic decline was gentle prior to the fall of the USSR, it was precipitous afterwards.