I seriously doubt that. Elites generally have other ways to upgrade - if the airlines wanted to make a change, maybe they could reprioritize so mileage upgrades don't get confirmed as early, but it would still be a ridiculous devaluation of the entire program to eliminate them for non-elites. It's in the airlines' best interests to allow low-level members to upgrade occasionally - once they get a taste of it, they may want to become elite to have more opportunities.