when it really hits the market
I don't believe he put that kind of timeframe in his claim. He just said it "will" be, as in eventually.
One of the ways he's aiming to save money is by making the manufacturing process more efficient, which I imagine won't be in effect as soon as the panels hit the market. Upgrading their manufacturing process for the solar panels will require a lot of capital expenditure, which they already have a ton of considering their Gigafactory construction and the upgrades to their Fremont factory. Not to mention, the statements made about building another Gigafactory in Europe or Asia.