how will the cost & safety side be handled
I never said Fizzer had to throw away the coin system for creating modded games. If Fizzer would make (some) mods accessible for non-members I would propose to leave the pay system as it is right now for members, but remove the weekly free game for non-members. This way members still have a small benefit from their memberships and still everyone can't create unlimited modded games
For the safety side, there is a mod ranking for a reason (although that is another topic, cos I would like to see it change a little). Only mods that are trusted (standard mods) and those in the promoted category shoud be available for non-members. I do agree that mods can break games, but those mods are (or at least should be) all in the experimental category.
Mods are community driven, it is also our task to watch an eye out for mods that become incompatible / outdated and report it to Fizzer so he could demote them. As far as I know there has not been a mod promoted or demoted in the last 6 months, which is I think due to the small community that actively use mods