I have no idea what "monopoly restrictions" you are talking about.
The big carriers (I was NOT talking about charters like Thomson and/or TUI) from Europe or the US will generally do the service from their own hub to a hub in Brazil, leaving local traffic to local carriers (maybe a partner). This system exists already for years and has really not much to do with monopolies, certainly since there are "open skies" agreements.
Unfortunately, for you guys that try to promote your interests in the NE property market, Natal (nor Fortaleza, nor Recife) was never a hub in that sense, and probably will never be. That is simply because there is not enough DEMAND, year around, for a frequent (say daily) service that is viable and profitable.
The new airport, it has said many times so, was advertised as becoming the biggest in Latin-America´s. For that to happen, it has not only to handle millions of passengers a year, but also tons and tons of freight. For the time being, it is not even operational, and that should give rise to some less optimistic outcome.
Very simple: the airlines plan their routes very carefully and at least a year ahead. They will NOT plan a route on an airfield that is not ready, or even authorised to operate.
Furthermore, as far as I understood it, the demand was really never there, the megaprojects failed because of that fact. So, you can´t speak of RETURN of demand.
I also think that the prices of properties in Brazil are almost nearing the ones from Europe. The only advantage could be the favourable exchange of the euro into reais, but that could change anytime, we have seen it before.