Thanks for writing in!
This information can be found on all the FAQs on our websites for the Smart Home products. We had to utilize a completely different architecture to be able to support the Alexa feature as well as some newer ones in the future. We currently do not have any plans on integrating the two different products lines.
If grouping the home theater system into the SoundTouch group is critical, I'd recommend what @Xyz987 mentioned and try to source a SoundTouch 300. They utilize the same drivers and can still use the new Rear Surround and Bass Module 700 accessories.
Tony A - Community Support