What would happen if wild boars went extinct?

If the wild boars went extinct the wild sows would cease to have offspring and the species would go extinct.If you mean "What happens if wild pigs go extinct?" then you would haven adjustment in the ecosystems where they live. Some predator species would find a replacement food or die out. Some plants which they eat would flourish. Some herbivores or omnivores whey complete with for food would flourish.

All of these would change the local ecology,

In areas where wild boars are really feral pigs which are escaped from farms - the ecology would return to closer to the pre-existing conditions.

Farmers who find wild pigs to be detrimental to their crops might be happy.