Those people who had experience use bitcoin will probably favor on this but those person who doesn't will surely have a difficult time to adopt. We can just use bitcoin as a currency if the government allows it first. Second if the world does know about it. There are still so many factors so bitcoin can't be legalized in some country. In the future I think we can use bitcoin or any altcoin as our currency.
Bitcoin doesn't answer to any government. So being "legal" isn't a thing at all. Thus, you can use Bitcoin at your will. However, the government is aware of it, that's why "regulation" is a thing. But the government is not directly who regulates it, but companies, who gained permits from the government to run as a "business". That's why exchange sites or even Bitcoin ATMs have fees.
BTC acceptance is growing fast, and it is becomming accepted in more and more places worldwide, but nevertheless BTC won't work as a form of payment right now, transactions are too slow and expensive, this is why the BTC community puts all the hope in lightning network...
but I think BTC is not supposed to become a form of payment, I think they are aiming for a store of value, which is something different...
It already is. Some wallet/exchange sites such as
Coins.ph have options for you to pay your utility bills. The transaction is not that slow, its only slow if you're transacting a large amount of it, but who pay their bills with 1 Bitcoin anyways(?)