In summary, salaries need to rise (and they are), and the tax system needs to raise its thresholds accordingly (and it hasn't yet?).

Note that the increase in housing costs has been largely driven by AirBnB etc, like much of the more desirable to tourists parts of Europe. Digital nomads (working remotely, almost by definition, and not getting paid that much in the grand scheme of things, again almost by definition) are somewhat incidental to all this, except as far as they might encourage local high skill job creation by some form of osmosis (e.g. bringing opportunities for locals to also work remotely though recommendation, and piquing the interest of outside companies in Portugal as a place to hire / do business).