Tesla may or may not start base model production in Q1 2019, but availability is not really helping the Bolt sell.
"Nobody wants one" is also hyperbolic - Chevy releases sale numbers, and while not top-of-the-line, they're also not 0.
Some high demand cars sell over MSRP. Seeing deep discounts at the end of a model year is common when trying to shift inventory or when dealing with very high margin trim levels. Advertising 26% under MSRP for a base 2019 model in 2018 is a rather extreme case.
PS: For some actual numbers: GM delivered 3,949 Bolt EVs during the last three months in the US from 6,710 units during the same period last year. In automotive sales terms that's very close to zero. https://electrek.co/2018/10/03/chevy-bolt-ev-sales-slumping-...