Candol: Let's do a thought experiment, shall we?
Imagine that a scholarly consensus emerged, which claims that much of what we know about Buddhism was invented only relatively recently - say, within the past 500 years.* How would that revelation impact your practice?
Off-hand, I'm pretty sure that I'd be disappointed. After all, one of the things that I find appealing in Buddhism is its antiquity. In other words, practicing it (insofar as I do) makes me feel connected, not only to other Buddhists around the world today, but also to thousands of years' worth of Buddhists. Thanks to that scholarly consensus, that connection suddenly looks a lot smaller!
On the other hand, I don't approach Buddhism the way an orthodox Buddhist does (say, like a devout Theravadan). Indeed, my approach is so radically unorthodox that I actually sympathize to a degree with those who say that it's not Buddhist at all! (I say "to a degree" partly because I think that these critics overestimate the stability and uniformity of religions.) Surely, a secularist/naturalist/scientific-skeptic like myself cannot also be a Buddhist!
But that aside, all of my Buddhist "teachers" are still alive today: writing books & essays, doing interviews for podcasts, speaking at seminars, running meditation retreats, etc. They are the closest that I've got to a "sangha" (even though it's a virtual one). More so than even Gautama himself, are they my buddhas! Sure, they all harness the power of myth surrounding the Buddha. But I am already aware that it is a myth (or at least largely so), so what difference would it make to my practice if it turned out that it's a much younger myth than I previously thought?
I could be wrong, but I don't think it would make one iota of a difference in how I practice Buddhism if Buddhism were much younger.
And, let's say we alter the thought experiment, so that the scholarly consensus is instead a claim of discovery of a document that's both older and much smaller than the Pali Canon, yet clearly serves as its source.
To be sure, I'd be interested in it. But the thought that I might alter my practice so as to conform more closely to the source - say, just because it's older - strikes me as kind of fallacy on my part, or a faulty way to lead my life.
Anyway, I should go to bed. Hope you receive this lengthy reply in the loving-kind way that it's intended.
* To serve a purpose (e.g. of thinking through an idea to its consequences), a thought experiment needn't be realistic, but this one isn't quite as absurd as it may sound at first blush. See: http://en.wikipedia.org/wiki/Invented_traditions