No, museum art and art antiquities should not be returned to their country of origin, because someone does not own something, simply because it is from the country they are from. Art is created, and it is bought and sold. People from a foreign country can appreciate artwork, just like people from one country enjoy learning about other cultures.
Many antiquities have been discovered and collected at original sites with the permission and cooperation of earlier resident governmental structures. New political powers in given countries should not deprive legal owners and global viewers of such materials. The possession and protection of the art treasures of the world should not be captive to present political whims. Art should be a world -shared entity and not subject to nation-state politics.