They could prefix the i with the generation year, to make it somewhat meaningful. "I have a 23i5" would tell most of what you'd need to know to figure out how well it's going to run a certain piece of software. It's also clear that a 29i5 should be a lot faster and more featureful. (Perhaps I should upgrade!) You'd still have to dive into the details to weigh a 23i5 against a 25i3 though.

For the complete SKU some more jibberisch can of course be added. Like 25i7-32mg. This suffix could be generation specific though, allowing for some flexibility. Most people wouldn't need to care.