The bottom line is that no there isn't a sufficient market.
Well that might suit Iberia, but they might have to think again, GC to South America is most definitely on Norwegians radar when the MAX arrives + the Caribbean from LPA/TFS
MAD might only be two hours away, but its two hours in the wrong direction, then aircraft change then two hours back to overfly where you started from, the market may be small, but i bet it will easily support a thrice weekly service on a 738MAX