Manni,
Majority of Sikh believers are non Keshdhari, so your first point is irrelevant!!
I agree with your other points.
The issue us one of education by parents, the lack of and influence of gurdwaray being central focus of the Sikh community, and the disintegration of the Sikh community. Gurdwaray these days focus on the wrong things and have become commitee focused, focused on power and greed, there are very few facilities for youths and the atmosphere in many gurdwaray make it very unapealling for youth!
Also we can also take into account the general 'westernization' of Sikhs, which has lead to a larger influx of white and Sikh marriages!!
Instead of attacking and blaming Muslims, Hindus or whites, we must first look out our own community, our own people!! Also, this isn't a new phemomenom, this has been going on for years, and there's no need to panic, it's still a small percentage but we still must be aware and tackle the issue!!