His proposal, which hasn't been fully released as of this writing at least, seems to have other modifications as well. The article mentions at least bathrooms a

His proposal, which hasn't been fully released as of this writing at least, seems to have other modifications as well. The article mentions at least bathrooms and elevators. He also plans to complete this overhaul in 5 years - previous estimates had suggested it could take 50 years. That sounds ambitious, and i'm guessing there must be significant cost associated with completing it relatively quickly.