Just change the law -- simple!

Forget the legal niceties and arguments that have little benefit to anybody other than the lawyers. We waste far too much time and money arguing what the law says, and not enough time and money considering what the law SHOULD say.

The general public doesn't care whether a chip has a valid patent or not. What it cares about is being overcharged for consumables.

The simple way to prevent it is to make it unlawful for devices which use consumables to implement technology which has the effect of preventing the use of third party consumables. Then it makes no difference whether a chip has a valid patent or not -- because the use of that chip would be unlawful in the first place.

First, change the law to prevent further abuse. The legal wrangling on historic issues then becomes substantially irrelevant.