Economic disaster? Hmmm....if you look at it in the broad, plant based diet would require less land for producing all the food needed and less pressure on the water supply.
Less stress on water supply too.. we have also picked up a lot of diseases from our close proximity to animals (insert your own joke about Tykes/Taffs/other favourite group).
I still eat meat, but am looking to reduce the amount I consume. Doubt I will ever go fully veggie (Chicken Tikka, Bacon butties, Chorizo and a Brazilian rodízio too good to say no to).