"Veganism and organic are quite incompatible"
Well it's a bit like saying homosexuality and society are incompatible. In both cases there is a place for both and nobody but extremists is pretending that one should replace the other for all crops. In both cases there are also middle grounds. The "gap" is not an antagonism.
Less beef does not mean vegetarian either, let alone vegan. There is no productive debate with such extremism. Organic consumers and farmers don't have only wrong premises, there are very good arguments to be respected in both types of farming. I personally think that the balance is on the organic side, including for increased food production, and I favor small local companies to global polluting chemical giants, but eventually it's up to the consumer to decide and to the farmer to adapt. Now if it's to replace the horizontal and vertical integration of conventional animal production with an organic equivalent, there would not be much to gain by switching to organics. But you can also view this as an opportunity to introduce new comers and reform the economic model a bit. Currently, there is not much incentive to farm when you have no control on the cost of your inputs and the price of your own production.
And there are vegan farmers too, I am sure they manage just fine on their scale, maybe with vegetal compost or mined P and K, even if it's not really sustainable in the long term. After all, phosphorus was first discovered in urine, of which we have an inextinguishable supply with all the coffee and tea and beer we drink... Brush compost is a great source of potash too (hence the "ash" part of its name when burning wood), it keeps the forests clean and less combustible, compost even generates heat or methane. Or we could probably get lots of potash from desalination plants if we manage to dissociate the different elements present in the slurry. It wouldn't be the only fertilizer that's a by-product of such industrial processes, like gypsum from the cleaning of coal power plants.