I think Alexa is in huge danger here. Siri & Google have some advantage being pre-installed voice assistants that can be natively triggered from mobile, but I actually have to buy into the Alexa ecosystem.
Personally, I have found Alexa has just become a dumb timer that I have to yell at because it doesn't have any real smarts. Why would I buy into that ecosystem if a vastly more coherent, ChatGPT-based assistant exists that can search the web, trigger my automations, and book reservations? If ChatGPT ends up with a more hands-off interface (e.g. voice), I don't think Alexa has a chance.
That was the whole thing about Alexa: NLP front end routed to computational backend.