Back to dystopia - Pedagogical planning
Let's imagine a place ( be it a nation, or a city, or a village ) where Esperanto becomes the most commonly used lingua franca - so much so that it is also used as a "working language" for almost all purposes.
In such a scenario - how to teach the language to new learners ( let's say immigrants to that place ).
Won't the pedagogical standards be quite different from what Esperanto teachers are following today ( in a world where most learners free-willingly opt it. When there is no external compulsion to learn the language )
How easy or hard will it be for those immigrants to go through all the necessary KER niveloj ( CEFR levels ) ?
The situation would be similar to Israel and Modern Hebrew, or Indonesia and Bahasa Indonesia. In both cases, only a tiny portion of the population actually spoke the national language at the time of adoption, and the countries had to figure out how to teach a large portion of the population a language in a short period of time.
I don't know too much more about the history of those cases, but I'm sure if you did some digging you could find out how the Israeli and Indonesian governments were able to turn minority languages into the national languages. In the case of Bahasa Indonesia, it probably helped that the language was already a trade tongue, and that the language is relatively easy.
In the case of Modern Hebrew, as I understand it the grammar was significantly simplified from Ancient/Liturgical Hebrew (so much so that some scholars think "Israeli" would be a better name for the language) so that it would be fit for essentially a whole nation to be able to learn and use it.
In answer to the original question, I have little doubt that in such a scenario any newcomer would find it significantly easier to learn Esperanto there than we do now, due to immersion. Most people who go to a week-long Esperanto event come out feeling a whole lot more comfortable and fluent in the language than they did going in. Imagine that for months, years or decades at a time.
Manĝu terpomojn kaj feliĉiĝu!
To answer the question - it would be multiply easier to learn the language in that situation. I'm not saying it would be trouble-free, just that it would be much much easier. However, if you as an immigrant come to a situation like that, but you don't want to learn the language, than you won't learn it, no matter how easy would be to learn it.