I am glad I found this thread.
WDC is working on its own fiat exchange (scharmbeck.com) to become more independent of Bitcoin which is one reason I support it.
It is a very good point you bring up though. We are very vulnerable. If Bitcoin were to die it would probably bring down 95% of the alts.
Right now Bitcoin is acting as the crypto reserve currency. With a few exceptions anyone wanting to buy alts must buy Bitcoin first. Anyone wanting to sell alts for the most part also has to go back into Bitcoin.
Bitcoin itself is benefiting from this because an increase in demand for alts automatically increases demand for BTC as well.
Also because of this effect Alts get hit harder then bitcoin during a crash because in order to exit an Alt to go back to fiat you have to buy BTC (increase in demand) then you can sell BTC (decrease demand) so there is a slight cancelling effect on BTC when there is panic in the market. Just like when there is economic problems or war looming the USD often gets a boost even though the US is experiencing similar problems.
I wish I had more to offer the thread but ideas are escaping me at this time other then what you already pointed out.
I did hear talk at one time of something along the lines of a p2p exchange. It would have to operate in crypto's only probably but it would provide insulation from the economic risk of basing an exchange in a country that could turn out to be unfriendly. Don't know if this is viable but it would be pretty cool.
Yes, the p2p exchange type thing is exactly what we need for a start. With exception to the coin design there has been no real progress in the mechanisms upon which crypto depends in years. I would have thought a decentralised currency would have led to a fully decentralised mechanism much more quickly.