Earlier quoted context omitted.
One possible consequence of a trend towards less formal ways of presenting mathematics is that the ease of entry to the informal might not motivate beginners to learn the formal. Consider that amateur mathematicians from the past, particularly those whom made great contributions to science, might not have been motivated to teach themselves the rigorous formal notation if everything they read was explained in layman's…
This comment keeps saying "[rigorous] formal notation" -- are you implying that new mathematicians might lack rigorous mathematical technique, or just that they won't be motivated to communicate their results in a formal way that other mathematicians will generally understand?
In a world with solid coverage of mathematical theory presented informally to appeal to a larger laymen audience, will the world produce more amateur mathematicians that make great contributions to science or less? Will would-be amateur mathematicians be less motivated to learn formal notation given that they can more easily read and understand the same material presented in an informal manner? If they did pick up a base level of formal notation, would they be less motivated to learn how to understand or write rigorous proofs using formal notation for the same reason?
I don't know what the answer is. Maybe there are studies out there that attempt to answer these questions.