I am having this question in my mind for sometime that did Satoshi ever thought to make bitcoin a mainstream currency? Or did he just wanted to create merely an anonymous commodity which could be used for transactions as a side line currency to fiat. I came across this idea actually when I was scrolling around the past posts of satoshi in the Economics Section. Here are a few instances when he quoted bitcoin as a Commodity and not as a currency.
He might not anticipate that it would explode like this in a short period of time, this was an experiment and he wanted to be anonymous and he just wrote the initial stuff and we really do not know how he would have sorted the transaction bottleneck issue if he was active, the reason he went off is because Wiki leaks started collecting donation in bitcoin and that spooked Satoshi and then when Gavin met with the authorities that was the day he went offline i believe.
Thats some really interesting info never knew that it happened like this but yes what you are saying is obviously correct that he might have never thought that it would become such a popular currency or means of settlement. But despite of that I think that we can still not think of making it something like a national currency due to scaling issues.
Probabily as good mentality to avoid all that he stated as to make fiat converted into something everyone could be using without any fuzz about such as bank conversations and government middleman actions.
You can already see it as a mainstream in practice where everyone is able to exchange with someone who you could not trade so simply as before.
With these exchangers we are able to be one step closer to our unknown buyers and sellers and that's what it makes already being a mainstream currency.
No matter how close we move towards making it a mainstream currency we would still be never able to achieve the dream of it. Solely due to the fact that Bitcoin remains a technical currency operable merely using computers or atleast mobiles while most of the world is still not able to read or write properly.