One of the challenges ahead for Alexa Voice Service enabled products is catching up to the services that are available on the Echo. Multi room casting, Alexa Calling — these aren’t yet available to Alexa devices. Notifications was just implemented on AVS, allowing third parties to have this feature on their products.
One of the benefits of Amazon having its own hardware is that it can test out implementations and interactions before it releases to third parties. The downside is that it might make third party hardware makers who are looking to do a unique implementation antsy that Amazon might step on their unique butterfly.
The other drawback of new features is that device makers will need to constantly think about long term integration and using hardware that can support future functionality.