Integrating foreigners into local populations is actually the only way to relieve pressure at this point. It's much harder for a homogeneous group to stand against the inexorable build-up of pressure alone because no matter how sturdy the definition of itself, time has a way of wearing everything thin. By having entirely alien schools of thoughts in its midst and yet be standing together, a group can spread its burden across different philosophies each with their own independent coping mechanisms thus creating an interwoven net of identities where no single faith/creed ever faces the pressure alone.
Unfortunately, these compromises can only slow the inevitable, they do not resolve anything.
As long as the us constitution and bills of right are the only supreme law of the land the us is safe. The problem is in the EU where some countries struggle with a basic concept like freedom of speech...