Bitcoin as a single currency will be a good idea. It can bring bad effect and can also bring good effect.
But doing that, will not be so easy. Because some country are not satified in bitcoin, because of its quality, of being volatile. It can bring big change in our economy. It is a long process, lets just wait and see, for now lets all enjoy bitcoin and support it.
You wrote a lot of text, but said pretty much nothing. Bitcoin as a single currency is an awful idea. It would collapse economies all around the world, there would be nothing to measure it against, and not to mention not everybody would have access. That would fragment the world wide markets and for that reason it can't happen. Alternative it will be, like gold is to fiat and we should all accept this. Doesn't mean though that Bitcoin can't one day reach a 6 or 7 figure price line.
Right on. Bitcoin as a world currency, considering the way it works now, is a pipe dream. One that would be neither feasible, nor useful, at least imo. A single currency implies association with a governing body. And only a global regulatory organization would allow this to happen and it probably wouldn't happen anyway since they wouldn't have much power over it, Bitcoin evolving in the same way it has so far. What we need to do in order to regain our freedom is create a multitude of currencies with various value conferring attributes (tied to a real-life usecase preferably) that would practically act as a safe net against censorship. This is a decent amount of years away, though.