This issue came up in a game of Cosmic Encounter tonight and we were unsure how to resolve it. The wild effect on the Sorcerer flare card allows the player to force the two main players (offense and defense) to swap powers. It then says this swap continues after the encounter is over. We took this to mean that the swap is permanent, which is pretty freaking powerful!
However, adding to the confusion was that the defending player only had two of his home planets colonized at the time, meaning that his power was removed at that time because his race was "non-viable." The attacker had three of his home planets, so his power was active. We could not agree on whether this meant the defending player would get to use the offensive player's power, while the offensive player would have no power (because the defending player "traded" his non-power), or whether the powers would swap but then the defending player would lose it immediately because they still only had two home planets colonized.
In addition, is the trade really permanent? That seems like a very powerful ability to be Wild, especially when the Super ability for the Sorcerer on the same card is relatively weak (allows them to use their ability to swap Encounter cards even as an ally)