90% of the world's wine production is intended for consumption within 3 years. My guess is less than 1% is expected to last 10 years.
Factors affecting longevity include high acid, alcohol, tannin, and sugar. Long lasting wines need the best fruit. Kits are not that.
A lot of the discussion here presents unrealistic expectations of longevity. This is not to say that folks are not making wines that will last 10 years. But those reds will have the above factors, excluding sugar. Or fruit wines with high alcohol and sugar, and probably acid.
I suspect Matt's estimate may be low, as he won't want to set unrealistic expectations. Me? I estimate 5-7 years. This is a brand new product, and these are simply educated guesses.
Be cautious of saving wine until it's at it's peak, as at that point it's declining. Put away a few bottles for later drinking, but overall, enjoy the wine when it tastes good. If you prove Matt wrong, I suspect he will be pleased.