That is pretty much the default future.

One question is whether it is technically possible to avoid it - even if you had a totally private AI assistant runnng on your own hardware, it'd need to pull information from somewhere and interact with online services, revealing a lot about you.

And then whether people would pay for it instead of using a free service that reveals everything. Internet behavior seems to indicate not, probably because for the most part having corporate AIs know all about one is more useful than harmful, even before considering all the free internet services it gets one.