I don't think they will. They have already expressed the iPad is their vision of the future of computing. A completely locked down platform allows apple to have full control over the entire computing life cycle and achieve results unparalleled elsewhere, whilst also making their product incredibly sticky.
I think Apple can and will justify it. If you think back to Steve's analogy about cars and trucks, there's still (obviously) a very healthy market for trucks.
Despite their ongoing efforts to make the iPad more capable, I think and hope they'll recognize the value in keeping it simple enough for anyone to use, and thus having a separate macOS experience with more tools/flexibility in a laptop/desktop form factor.
