In El Salvador process was not done the way it was supposed to be, the government should have created the awareness of Bitcoin and it's benefits to the citizens before the adoption. It was lack of knowledge that made the citizens withdraw to 10% of it's users when Bitcoin plummeted.
The government should have study her people and understood what should have came in first before the adoption of BTC.
El Salvador has gone past that stage now. Currently, people are aware of the benefits of Bitcoin and more awareness is still going on.
Now it is up to the citizens of this nation to choose between fiat and Bitcoin. Those that are interested would definitely grab the opportunities and options that Bitcoin offers.
Of course, when bitcoin is present the citizens (and anyone visiting El Salvador) can choose to use either the dollar or bitcoin, and they do not need to choose one or the other (of course, unless the option is not available, and some areas have more adoption of bitcoin usage than others - and maybe there are not too many locations that are already set up and used to transacting in bitcoin and/or lightning network?).
Personally, I think that it will be a good thing for citizens to be able to hold value in both bitcoin and fiat.. especially if they start to get accustomed to hold bitcoin and to figure out how much to hold and maybe how much bitcoin to keep in their bitcoin wallet versus a lightning wallet.
Holding value in fiat value would be for shorter-term cash expenditures and maybe for a large number of El Salvadoreans, there is not much savings after holding value in dollars and even an emergency fund in dollars. Nonetheless with bitcoin there are options that would possibly involve attempts to allocate some amounts of savings and investment into bitcoin over longer periods of time and then just to be attempting to spend strategically from the bitcoin holdings.
There is no exact one formula that anyone might use for deciding how much to hold in bitcoin as compared with holding some of their value in dollars because there are needs to account for a variety of individual circumstances such as cashflow, other investments, view of bitcoin as compared with other investments, timeline and risk tolerance.