When the brothers don't great each other is a sign of the Hour.

Abdullah Ibn Ma'sud related that the Messenger of Allah (Salla Allahu alayhi wa sallam) , dijo:

" It's true that amongst the signs of the Hour is that the greeting (of Islam) will be limited to those known only."

In another report:

"A man will give the Salam only to his intimate friends."

SOURCE: Hadeeth of Ahmed.