Sure, the more you make the cheaper it gets, basic capitalism. BTW, Trump meant as do all coal supporters that the cost of renewable energy ‘at the moment’ is unsustainable. Not to mention the places that produce renewable energy is sufficient quantities are the best places to have them in. The next step is to see how it would do in all areas.
Elon Musk said at the time he introduced his new designs of solar houses that in the future we could only hope to have an economy of 40% renewable and 60% coal & nuclear. He was talking about the current technologies and the new potential tech as well as the practicality of harnessing this energy just not being sufficient to have a 100% renewable energy economy.
In other words, 50 years in the future and millions of jobs losses later we can still only get to about 40%.
What’s heartening is that this would still not stop Global Warming because it does nothing for the natural factors.