you're right. dollar is the most stable currency in the world. anywhere in the world, you can use dollar in purchasing things compared to any other currency. in short dollar can be consider as a worldwide currency.. i dont think bitcoin will be able to replace it. bitcoin is still new even if compared to other currencies which is in low with dollars. there still need a lot of work to do with bitcoin in order to replace any currency especially dollars.
Well bitcoin has its own use and a lot of great features but i think it still can't stand on its own and would probably depend on the dollar or fiat in general to survive. If we're looking at the next 10years, i don't see any way that btc or any alternative currency can replace the dollar. Though we may be looking at a great alternative to do transactions with the emergence of btc