I think the way they could compete is by having on-device handle a limit universe of queries, and then use some souped-up Siri for the rest. Currently iPhones can do some Siri commands even when offline, for example.
Hell even the most recent Apple Watch does some Siri commands, including voice to text, on device. Apple is certainly pushing low power on device processing with their own custom chips (S9 on the watch I believe).
Yep, I could totally see them enabling this only on Pro-level iPhones, for example. This would presumably be because Pro devices could have different chips that are designed to handle these specific tasks, as well as having larger batteries.
I expect there will be a lot of iPhone upgrades this fall, as buyers will finally see a difference between their 1-3 year old device and a new iPhone.
