That's not the point though. Almost all futures traded are settled in cash. I've been trading futures for a living for the last 10 years, I've never taken delivery of barrels of oil, or cotton, or gold.
This is true, however the primary difference is that the price of the commodities that you listed are decided by the price in the futures market. Whereas, the price of Bitcoin in the futures market is based on the real price of Bitcoin on the exchanges.
The a large dip in the future contract price will cause trader on the open market to slow down their buying of bitcoin, pause, or sell off to an alterative investment, this is where the rise of other coins will come in.
Certainly a possibility. There will be some sort of impact. I'm really just trying to point out that it's not a 1-1 relationship...