Earlier quoted context omitted.
I felt like that was implied by the usage of AGPL: if Amazon wanted to start using this and apply patches on top of it, the AGPL would require that they share those patches with their customers, which would allow Elastic to integrate them into main again.
I don't think that's their intention. Elastic wouldn't be able to integrate Amazon's patches back into their codebase without losing the ability to change the license in the future. Even more, since it's AGPL, they'd have to get rid of their other licenses immediately.
(I anal, even if I were a lawyer, I am definitely not YOUR lawyer, yada yada)
If I were Elastic, I would require Amazon dot com or anyone else who wants to contribute code to Elastic to sign a CLA. Depending on how the CLA is structured, this could allow Elastic to continue multi licensing?