I use Bitcoin because it is usually simpler and faster and cheaper and more secure than all other ways of international money transfer.
In my opinion the future is legal. I sell coins every day to people who use the coins to pay for services or as a store of value / investment. Nothing of this is illegal. And the value will of course drop to the bottom if Bitcoin is deemed illegal. Both I and most other people will get rid of all we have as soon as possible, and it is going to be hard to do it in a legal way.
Simpler? Than going to a bank and doing an IBAN transfer? Man, cheaper maybe but not simpler. Getting money in and out of Bitcoin is an extreme hassle for most people.
Yes, simpler. I can get loaded up with coins with one simple IBAN transfer, and use the coins for many smaller purchases. Getting money in to Bitcoin is not any more difficult than
one IBAN transfer. And I make it even simpler for people in my country by offering coins at a low rate for domestic bank transfer. This enables people who don't know how to do international money transfers to get their coins in a very simple way and very quickly. Buying coins from me, asking me to pay directly to the address they want to pay to, is always faster than any kind of international money transfer through a bank. Credit card may be faster, but not as secure. And not everyone want to pay everything with a credit card for various valid reasons.
I don't think, for most people, it's a substantially better way to transfer money internationally. It's pretty slow, there is a hassle getting money in and out the system, and transfers won't be free forever.
Slow? Compared to banks? Have you ever done an international money transfer? It takes 4 to 5 days to transfer money to Japan from here. A Bitcoin transaction has 6 confirmations in an hour by average. And there is
no risk of fraud. Nobody can take the coins back when they are sent.
Plus, for people to use Bitcoin to transfer money, they need to be aware of it, and they need to make a special effort to use it. Why would anyone spend money in order to market the system like that? They would need a reason, and that means exchange fees.
A lot of people do. I've sold bitcoins to more than 400 people. IRC and e-mail.
As to your 2nd point, if Bitcoin is made illegal somewhere then the value will soar. And of course people will be able to use it legally in another country.
I proved the opposite in simple economic terms in another posting. Demand will go down. Supply stays exactly the same.
Other factors which will also contribute to the fall if Bitcoin is made illegal. Development will stop. A lot of good services will stop. Exchanges will shut down. People with a lot of coins will obviously try to sell before the exchanges close their doors.