We're not using the pack finish rule.
If I'm reading them correctly, the new upgrade rules kind of do what your suggesting. They extend the top 10 finishes concept to pack finishes for fields larger than 50 (most of our races around here). Once you have 20 pack finishes you can upgrade from a 4 to a 3. Maybe if Casey reads this he can give us a strict definition of a pack finish.
While in theory this should ease some of the points pressure, I know a lot of people would like to consistently finish well before they upgrade so they would like to upgrade with points.
Races selling out may ultimately drive some to upgrade (myself included) if Cat 4's can't race as often as they like.