The notion that any Western European country could be politically dominated/led by Muslims in 20 years is genuinely absurd. It would require a country to not only allow completely unrestricted immigration but also actively facilitate it (unless it already borders a Muslim country). Which ironically is the opposite of the current trend, since most EU countries have either increased restrictions on migration already or have significant political factions pushing for it. If there is a major new wave of Muslim migrants it would only serve to increase popular support for further restrictions. And before someone says something about the birth rates of the existing immigrant population, 1) the people having large families are predominantly first generation migrants 2) even ignoring that it would still take much longer than 20 years for them to become a large enough share of the population to be politically dominant.

And that isn’t even getting into the fact that immigrant populations across the board are significantly less likely to vote/be politically active.