Regina should never be underestimated. It is highly doubtful that she will still work with Rumpelstiltskin in the next season. He planted evidence on Regina for Kathryn’s kidnapping and he was going to leave town and let Regina suffer the wrath of the town when the curse was beginning to break. The last episode showed how much her distrust of him had grown since the earlier episodes.
And keep in mind, Regina has her own trump card: Rumpelstiltskin made the curse, not her. If she tells everyone who the maker is, they will be out for him as well. Granted, Rumpelstitlskin is very powerful, but he was held in the cell before–it could be done again if done right.
Even if the magic was made from True Love, Regina will still gain her powers back. She had obtained them before, she will do so again.