Amazon went to the trouble to purpose build all the parts and pieces needed to work this out inside the form factor of the product they are selling... Physically I don't think you will ever find components that will allow you to fit a separate hub inside an existing Echo. The spaces inside the original echo are pretty much used up with poor sound quality design and the original microphone array and what is already in it. I think they probably will be quite different inside when you are able to see the new echo with hub inside...