First there is technological unemployment. In the span of the next *few* decades most jobs will be replaced by machines, automation, new software suites and robots. This will be an extremely difficult transition, and the nett effect will b a substantial decrease in available work, especially low-skilled labor. The effect of this will be that the various countries of Europe will have trouble offering work for its own citizens. Whatever few jobs remain will be absolutely covered by a small remaining trickle of eastern Europeans. Migrants, most of whom have no discernible job skill, limited language skills, very limited cultural affinity or relevant work experience will have absolutely zero chance to get a job, and most these people will be left asking for welfare as a result. This will be deemed completely unacceptable to European voters. European voters will demand redistributive infrastructures – such as a basic income – and likewise they will most certainly not want “foreigners” to also get a basic income.
Second there will be a massive and very painful transition from fossil fuels to electrical energy grids. These involve systems that involve prefabricated parts and require very little and only highly trained engineering/construction labor. The nett effect on global (not merely EU) society will again be traumatic. All of the world will have less surplus affluence. The pie for many countries will shrink. This means that (aside form having less spending freedom for integrating and providing initial necessities for migrants and refugees) EU society will want to consume less goods. Lifestyles and expectations will have to wind down.
Third, and probably most important will be life extension. Life extension will be a certainty and biogerontologists are only bickering about the when. Many in the field are know very certain that life extension (most at first, statistical benefit of only months to years) will emerge very soon. From then on investments in this field will sharply increase and by the 2040s we can expect rejuvenative therapies. By 2100 almost no one will die of old age and all people in the EU (or US) you’d care to meet will have visibly young bodies.
THis will completely destroy whatever available jobs are left – as highly educated, experienced, healthy, youthful, optimistic seniors will enter the work force and scoop up all remaining jobs that are left. In such a society migrants will not stand a chance, and since a society with a massive surplus of working health physiques will be quite conservative, voters will demand stability, a strong respect for the rule of law – and that means less migrants. Europe will soon start having a much higher population growth rate, since less people will be dying pet year than in earlier decades.
Yes, people in europe are prejudiced and yes, people will assume migrants are first and foremost a challenge in terms of integration, education, health care, policing, etc. etc. and people will vote accordingly.
So no, the trends are Europe will stick with its choices and migration inwards will somewhere in the next few decades completely end, expect for a very few with scarce and high paying skills.