He picks 2015 for two reasons.
First, this is the year that bulk ‘trekkers’ (my word for the crowd arriving in Greece and walking north into central Europe) start to occur. By the end of the year....roughly 1-million have made their way into Germany. I sat that summer and could see working class Germans asking questions which the political figures could not answer (like how much was this going to cost). You could sense that the no-crowd was now a problem for the political folks.
Second, the 31 December 2015 event in Koln. Massive mess, 1000 police reports generated the next day, with this migrant male crowd that night. Over the next two or three months...the public TV crowd (two networks in Germany) were unable to carry a pro-migrant message anymore....the public simply weren’t buying into it, and there was fear that the public might go and yank on the ‘dump-the-public-TV-funding’ deal.
What Trump said in 2016 really didn’t matter in Europe. The atmosphere and public support for bulk migration/asylum simply wasn’t going to work again.
Thanks. I think there may be some small hope for the survival of Austria as a European country. Their changing views may well just be coincidental with Trump’s appearance.