Brandon is publishing the Kindle edition directly. I haven't hammered out the timeline yet with him. There may be a short delay for various reasons, or there may not be--but I don't know when or whether there will be preorders for the Kindle version or if it will be for sale as soon as it appears. I can tell you now that it will be DRM-free.
There will also be an audiobook version from Recorded Books that should also be available via Audible.