Australia had (has?) the benefit of feeding China (both actual food and minerals and other resources). At some point China will grow like a normal country.
No one said it's a rigid guide, it's just a bit of a signpost.
Could we double or triple the length between recessions? Sure, but I doubt it.
There's no rigid guide that the US expansion has to end anytime soon just because ten years was the longest expansion in the prior century. Perhaps this one will last 19 years and set a new benchmark, who knows (answer: nobody).