In my opinion, most reputable historians are trained to be cautious types who avoid sweeping subjective generalizations about vague terms and try to think with some academic rigor. On that basis, "great nations last x-y years" isn't even a statement that can really be evaluated as true or untrue with the intellectual rigor historians like to employ.

What is greatness? Is this even something objective enough to measure? What is a "Nation"? Is it a political system, a "people", a culture? How much change has to occur before something hasn't lasted? It would be impossible to define these concepts in such a way that all historians would agree on them. Even getting 10% of historians to agree would be improbable.

TL:DR This statement isn't true in so far as it represents historians reaching a consensus. The second clause is simply too vague to evaluate. It's really just a bit of a rhetorical flourish on the part of the author.

Wouldn't even a cursory glance at Egyptian and Chinese histories disprove this?