Siri will always be bad if all it will ever be is an "on-device" AI assistant. Without deep cloud integration it will never compete well.
Apple is trying to avoid the idea they need access to some of your information available on their cloud servers in order to make Siri a good product, so they are hyping up this idea that your phone becomes a highly specialized AI neural network, which sounds great for marketing, but in reality all it means is that Siri will find and access stuff on your phone with a massive amount of excessive engineering involved.
What Apple needs to do is recognize that there is a good balance between access and aggregation of your data vs having too much private data at their disposal, but I don't think Apple will win in this market if they draw a line land bury their heads in the sand and try to put all the power on your phone instead of taping into the power of the cloud.
I do not believe that an all or nothing approach Apple assumes about accessing consumer data is a wise business decision. Apple is hiding away from the real technical challenge of finding the right balance to make Siri a competitive assistant, so they are hyping up some nonsense AI neural network ******** that will be built into iPhone which will make is suck just as bad 5+ years from now if all it can do is scrape data on your phone and find a song or picture or web link for you.
This is once again a situation where an Apple CEO sticks foot in mouth and makes a huge public claim about how Apple will never do something, and that forces the companies hand for the next decade. Tim Cook went too hard trying to make Apple the darling of consumer privacy rights groups so now Apple will never be able to compete with Google or Amazon and try to trump up some BS iPhone AI technology platform claim trying to promote more iPhone sales in the future (and an increase in their prices as well), while Google and Amazon continue to advance their platforms by fully leveraging cloud integration.
This also isolates Apple from risk, such as what Facebook is challenged by now; by never TRYING, Apple never has to worry about failing, but its companies like Facebook that trail blazes and will ultimately strengthen the market by exposing critical failures and correcting them instead of companies like Apple that hide from innovation and wait until others have failed to figure out the minimum to move forward with.
Those who can't go into PR. Apple is the king of PR. I don't need massive amounts of AI to play a song on my iPhone, I want Siri to at least match capabilities of Google and Amazon, but it will never do so being an on-device assistant.