Refer to Indian states. The languages across most states are actually mutually un-intelligible and cultures probably much more dramatically different than anything in Europe. In most of Europe, the majority culture have common elements of either Catholic or Protestant or Eastern Orthodox Christianity.

True, but I don't look at India as a success.

I really don't want Europe to look like India in any way, administratively, politically and logistically speaking. Not to mention the countless tensions you can feel accross the country when you travel there. It seems like a ticking social bomb when I go there, and we don't have the class system to shut up lower classes and women that keeps the uniquality stable.

The partition of colonial India was anything but a peaceful road to co-existence. The consequences included over a million dead, and tens of millions of people displaced. Last time I checked, India and Pakistan shelling each others' positions is still so commonplace that it's become a meme.