He said that he hoped that they might be lifted by then, and he based that on what his doctors were telling him.
He is trying to instill hope as a good leader should. He is also paving the way to start transitioning back to normalcy as soon as possible.
As a liberal, government shut down of your personal freedoms and work might be a dream come tru, but this has been very traumatic, and potentially lethal to our economy. The longer we wait, the more danger that the economy does not recover. Unless you are hoping this kills the capitalist system so that socialism can finally take over our great country, then waiting to too long to come back to work is a very big concern.
One has to balance the impact that shutting down everything in our country has against the health risk of an epidemic that might soon be shown to be much less than expected, and for which the exposure to everyone is inevitable anyways.
The absolute ONLY reason for social distancing is to delay and spread out exposures so as not to overwhelm our hospital system. Once that risk is gone, we should go back to normal and allow the advantages of Herd Immunity in the healthy population to take effect while continuing to quarantine those at high risk only.