As for the "younger voters move to establishment parties as they get jobs/houses", that hasn't necessarily always been the case (see Germany), and the counter argument could run that as more and more people become "stuck" in precarious jobs and excluded from home ownership might mean they keep choosing radical options. But that is pure speculation.
etc. I quote the most interesting part to me. It's a good question about Macron. I think we have to accept that the under-25 demographic in most of continental Europe finds anti-foreigner politics very appealing.
Nothing in comparative politics is necessarily always the case, but mostly people with families and property become less radical, and older people become less radical, radical political positions are usually under-served by parties, and the parties that do serve those positions are less able to mobilise votes nationally. I wonder if any of these is particularly controversial, 90% of the time. IOW, you would expect to see radical parties and non-voters with a lot of inter-movement, if you could really observe it (Which is hard).
So, Germany is quite exceptional because they added a Communist dictatorship to their country in the middle of all these time series. I don't know if quite the same secular decline in CDU votes happened in the West.
However, I wouldn't be surprised if the young people without secure jobs or housing tenures remained radical for the duration of that period.
Double however, is that, the last phenomenon is not going to continue until they're, like, 50. This job precarity phenomenon has been going way down in European countries where the economy improved. The main problem with housing is what young person under 30 wants to live 5km outside a minor city, or 15km outside major cities, yet that's where the post-war housing is (often 1 old person with 2-3 bedrooms).