Violence exists not out of necessity, but basically because we like it.

This is similar to sex and reproduction. Animals reproduce not because they consciously want offspring, but because they enjoy the process itself. Likewise, violence is often enjoyed for its own sake, rather than for its material rewards. However, for humans the invention of contraceptives made it possible to decouple reproduction from sex. Similarly, once violence becomes unnecessary people will still find it enjoyable, but it may be possible to replace the actual violence with surrogates (e.g., sport contests or computer games).

Ceding low means fracturing a country, and people will not like that, because they reify and essentialize their country/government (nationalism).

This is certainly a problem, but are you convinced that it is unsolvable? In Europe, many countries already have strong separatist movements (for instance, Lega Nord in Italy). I am not aware of any popular political movements with the opposite goal (making their countries more centralized).