I foresee a collapse of BTC value when the first large financial institutions release cryptocurrencies of their own, which are actually backed by tangible assets like gold or by fiat currencies.
What do you mean by "backed"?
Backing a virtual currency by a physical commodity implicitly means that the "backer" has the power to generate coins as he wishes.
Cryptocurrencies don't need any tangible backing, as they're backed by mathematics.
Sure, financial & political institution will try to ride Bitcoin's success, and create their own versions of "crypto" "currencies", but it won't be nor "crypto" nor "currencies".
As soon as people understand the difference between trust and proof, they'll say goodbye to the fiat schemes.
If institution X created a cryptographically secured proxy for gold, $, wheat futures or whatever, and its widely available and accepted, its a cryptocurrency. Thats the OP's premise, that the primary advantage of Bitcoin is the secure, trusted, transfer of funds. Now, many would not agree this is the only purpose and say there are alot of other reasons, but its a fair point it is one of the major advantages. Take that advantage and replicate it in to some thing that is trusted and easy to access/obtain/reimburse etc and you have something which will possibly have larger mainstream acceptance than Bitcoin.
A large amount of the value is based on speculation that Bitcoin is destined to become common use and therefore highly valuable (due to limited supply) and you lose that speculative value if a common replacement is in use.
There are 12e10^6 in existence, at least 25% which are not in circulation, somewhere between 1-10 million users seems an OK approximation ... =>the average bitcoin holder has ~ $1000 in bitcoin ...
ummm doesn't sound all that speculative to me, more like pocket change found down the back of the sofa, maybe the cookie jar cash kitty has gone into bitcoin.