Agree with this although I certainly wouldn't call sales strong because if they were you wouldn't see these kind of discounts...The web site says this is factory rebates off MSRP not a change in MSRP. My guess is that this is indeed the case and that the MSRP is not being reduced, though the rebates may hang around. The reduction is not available for leases, suggesting that this is a way to make buying more attractive. If there would be a reduction in MSRP it would be more likely to happen at the introduction of a new model year. This is especially true given that sales are relatively strong at the moment, making it difficult to understand why GM would change MSRP now.
But you never know.