wow...
Let's not read too much into this. Certainly $70K for a minter '91 is great news for any early NSX owner but remember that values established by KBB, Edmunds, NADA, et al are based on market averages. This one is WAY off the bell curve. IMHO, I would expect the effect of this one sale to be minimal.
Cars at those auctions always tend to sell for bizarre prices.
I think for the money there are a few cars of the same vintage that might be just as collectable for less money, strictly from a collectors standpoint. 850CSi comes to mind.