PEW research has published predicted population percentage of Muslims in Western Europe by 2050
Edit: Some clarifications
Any one who is either of Muslim faith or from Middle East ethnicity is being asked about.
Any body who lives and is a citizen of Western Europe is a Western European. Same thing applies to UK and USA.
So what percent of the former is there in latter? How would it change by 2150, 2200 or if that's too much in future then any time frame in future, which is atleast 60 years from today, where it is quite reasonable to make this projection.