Updated Silicon is a given, and I think FaceID is eventually inevitable. We can probably also expect any hardware updates to things like HDMI, BT and WiFi. I don't think we should expect substantial design or hardware updates every year or even every other year. This is a computer and not an iPhone.
The M1 Macs are still selling well and running circles around the competition. This in combination with the chip shortage and fact Apple hasn't migrated their entire line over to Apple Silicon, makes me think we won't see upgrades annually. Personally, I think Apple will keep consumer products (Macs, home items, AirPods, wearables, etc.) in the Fall, and then pro products (iPad Pro, Pro Macs, etc.) in the Spring. This trend has more or less held true in recent years, and allows them to stagger releases. Consumer products sell better around the holidays, but pro users will upgrade regardless of time of year if they need the performance to get the job done.
This would mean M2 Macs (Mini, Air, iMac) next fall, with the Air getting a redesign and maybe the Mini too. If Apple sticks to their transition timeline, the Mac Pro will need to see new silicon by next fall. If they release the Mac Pro prior to next summer, I think it will be a souped up version of the M1 Pro/Max. If by next Fall, perhaps it will be a souped up version of the M2 Pro/Max, since the M1 family of chips will be 2 years old by next fall. Then we'll see the M2 Pro/Max in the MBP in Spring 2023, which gives it an 18 month shelf life and is reasonable given the M1 MBA and Mini will likely be 18-24 month old models.