After a weekend of angry comments, the official decision has been to hold off on this particular change and the premium pack until the developers can figure out another way to handle the changeover. Good news for players who didn’t want to lose out on their freeform slots during the change, bad news for… well, no one, really. Not every game with an optional subscription is created equal.
Greetings, Champions. After listening to your feedback these past few days, we're taking a harder look at the Premium Pack and how to better implement it. We'll have more news in the future, but for now this will not be launching on June 7th.
— Champions Online (@ChampionsFFA) June 4, 2018
Source: Official Forums; thanks to Robenix, Sister Silicon, and Zen Dadaist for the tip!