What would it take for a major player in the the field of eCommerce to accept this? Let's say an Amazon.com, Newegg, etc. Any guesses to what would happen to the value of BTC?
I think Bitcoin has a future as a transfer medium. Person A converts their money into BTC and sends it to Person B, who immediately converts it back into "real" money. As long as the conversions are close enough together, the actual value of the bitcoins doesn't matter.
Sure, some hardcore users will continue to hoard and speculate. But in my opinion, the real value of Bitcoin is as a secure, anonymous, digital means to send money.
My, granted ignorant, assumption is that BTC would keep revaluating each time a big organisation adopted it, but that "reaction" would smooth out as more and more organisations adopted it and its value settled.
So, yes, initial pain, but surely all interested would know and accept that in advance. As usual, early adopters accept the pain as it were. But early adopters in general are up for that for the thrill, if you like, of being there at the beginning. A bit like people who buy Tesla cars. They know its not perfect and that there will be some pain, but they love it anyway.