I believe Bitcoin's "fluctuating value" and government policies are factors that greatly affects its ability to be widely adopted in the mainstream world. If it wasn't by that, most people would've already joined the game. Despite Bitcoin's underlying "issues", popularity's been increasing at a slow and steady rate. Right now, Bitcoin is much bigger than it was a few years ago.

For the first time in history, a country adopted Bitcoin as legal tender. Everything seems to be heading in the right direction, so I wouldn't be surprised if Bitcoin reaches a level of adoption comparable to that of Fiat in the long term. No one knows what will happen in the future so the best we can do is hope for the best. Just my opinion