If we assume that we are living in a world of balanced ecosystem then changing the whole world to Vegan will provoke adversity. Also, animal products are considered important from health nutrition point of view. So, what we can do is to come to a mid-way between cruelty to animals and a " Vegan World". This could be done by establishing a law for regulatory body like FDA to approve only humanely killed animal products for their commercialization. And we as a conscious creature would only consume such products!!
Please kindly support this cause, Thanks!!