Just a thought.
One issue in maintaining compatibility with "retired" OSs is the huge range of possible configurations, updates, third-party software, and the combinations of all of these. It makes compatibility testing a nightmare and in the end, you still get complaints from people with configs you didn't test for and/or didn't even imagine!
I hope it won't come to this, but if the point is ever reached where Alwil developers are considering dropping support for 95 or 98 completely (if in fact it's not "never" ), a list of the configs under which Avast was successfully and unsuccessfully tested could be published. Users would then have the choice at the point of installation, whether to make the necessary changes, e.g. uninstall potentially incompatible software, or not install the new version of Avast.