The best I could hope for is for Bitcoin to become a widely and actively used currency that exists as an alternative to fiat currencies, in parallel to them. I'm not cheering for a state-mandated use of Bitcoin.
But as for the usage of Bitcoin for everyday transactions - the biggest problem, aside from network congestion and associated high fees, is that only a very few people earn income in bitcoins. And nobody will be buying btc for fiat just to spend it on goods.
With Bitcoin being marketed as "digital Gold", we can never expect it to replace Fiat. Can we? Most people nowadays only invest in BTC with the hopes of becoming rich quick. It's seen as an investment tool rather than a currency. Besides, BTC's limited transaction capacity prevents it from being used as such. True digital cash needs to be scalable enough to handle high network load on a daily basis. It needs to serve the needs of people all around the world.
Bitcoin is decentralized, but it lacks convenience. On the other hand, "shitcoins" are convenient but they lack decentralization. Then there's the issue of governments putting "obstacles" to help prevent people from using BTC on top of Fiat. With this in mind, Bitcoin will always remain an alternative currency (instead of a direct replacement of Fiat). Perhaps, that's the reason why Mike Hearn left Bitcoin?