I think after Apple's announcement today, Sonos might feel more pressure to push the Alexa integration for release. I hope Sonos figures this out soon.
2. AirPlay 2.0
AirPlay 2.0 is a direct Sonos competitor, although I am not sure how well it will work, at least right off the bat. For example, without a 'bridge' or 'boost', I am not sure how smooth AirPlay 2.0 would work in big houses. and would AirPlay transmit whatever sound from my phone (ringtone, youtube video, etc.)?
Overall I don't think most potential Sonos customers would go for HomePod instead. It doesn't offer a full home theater solution, and it's expensive (for the price of one, you can get two Play 1s right now with the promotion, and stereo sounds so much better). If Sonos can announce Alexa support soon, it would be a no-brainer for anybody in the market (an echo dot is only $40).