I hope so but some people don't like changes and BTC prices are too unstable for it to take over. What if your transfer drops 10% in value before it reaches its destination?
Banks can control losses and gains if they use Mt Gox. If a person wants to do a bitcoin wire for sending $100USD to another branch of the same bank, then the bank does the bitcoin transaction internally and has great control over the losses and can guarantee the that $100 will be given on the other end. Plus they make up for any anomalies by charging a fee. The Block chain message service could also be used to direct bitcoin transactions to accounts of other banks, wells fargo --> bank of america for example.
Banks won't do Bitcoin-transactions instantly for the same reason that they don't do regular wires instantly. There is no technical reason why wires take as long as they do. Banks are for a large part conservative institutions that won't evolve unless forced to. And since fractional reserve requirements mean that banks can loan out more if they have more deposits, they have every incentive to delay outgoing wire transfers.
Correct. Which is why we have Western Union and MoneyGram and for online purchases PayPal. Bitcoin can provide transfer services in place of all of these.
As far as bitcoin being a variable amount, the same could be said for buying foreign currency at your bank. The bank posts an exchange rate that can change. The same could be said for money transfer services using bitcoin.
For example, if you wanted to send 100 dollars or 100 German marks or 100 yen or any currency you would simply calculate that amount of bitcoins and send that to whomever was on the other end who needed cash. That person would cash out using coinbase.com or some other bitcoin cashing service. No bank or government ever needs to know what happened.