This looks like Amazon FUD. The revenue from alternate clouds will be tiny compared to running in AWS, so there's not much motivation internally to follow through. Also, to make money on other clouds you have to go deep on the products and offer value adds on top. That's not the Amazon model and anyway would be difficult to implement outside of a small number of products. Ergo, this is not something they are really going to do in a meaningful way.

MS SQL Server is a historical analogy. Microsoft could have run the table in the database market by porting to Linux but took years to overcome internal inertia required to run outside Windows.