The US dollar is at the top of the food chain, so to speak
And obviously cannot beat it, even as an online payment tool. But how many currencies are there? Maybe, the Euro as an addition to the dollar, and that's pretty much all. So is competing (or at least, trying to compete) with major currencies at a world scale level. The rest is mostly just trash in this respect (i.e. not very usable as a universal world-wide means of online payments)
Correct. It would be very difficult for to compete with major fiat currencies like USD, since most people only know about the traditional payment system, and probably haven't even heard about or other cryptocurrencies. Not to mention, lacks several properties that physical cash, like fungibility and others.
For to be able to compete with worldwide currencies, it would need to scale up to a point where it could handle large transaction capacity, while at the same time providing privacy features. With cash, you would have more privacy over your transactions since it is fungible. But, maybe one day BTC would get improved up to a point where it can provide true privacy, and a faster means of transacting between parties. Just my thoughts.
