Convincing meat eaters to convert is going to be hard but just getting McDonalds to make it special on their menu could make a vast number give it a go and once they find it to be just as good or even better, and eventually cheaper, then a good portion of that resistance will have been overcome.

McDonalds gets hit disproportionately by anti-capitalists and environmentalists and is always trying to improve their green credentials so I'm sure they'll be working on their own recipe.