Yes, I would say the meritocratic consensus is under threat today, primarily by interests that want to change the demographic makeup of these countries. It is happening in Canada as well, where the Eastern establishment is increasingly leaning on immigration from Africa to carry itself politically.
I wouldn't be surprised if it turns out that post-war immigration, whether it was based on meritocratic selection or not, was at most either marginally beneficial or neutral to the existing population in countries with high immigration. The last time immigration made a clear positive economic impact was probably during the much-maligned period of colonialism, where Europeans and especially the British were so advanced that they brought with them skills, knowledge and technology that propelled many of the colonised countries to the very top in terms of living standards. No post-war immigration wave, whether it came from Europe or otherwise, comes even close.