I don't know how close to (or far from) death Fr. Feeney was when Rome lifted his controversial 'excommunication'; but Cardinal Medeiros of Boston requested the Holy Father lift the excommunication when he heard of Fr. Feeney's illness with cancer. Cardinal Medieros admired Fr. Feeney and felt there was no reason why such a good and faithful priest should have to suffer excommunication. Rome agreed.
You're also correct about Fr. Feeney's excommunication being lifted without any requirement of him renouncing his teachings on extra ecclesium nulla salus. All he was required to do was recite the requisite prayers, which he happily did in four languages including Latin.
I have no doubt that one day the great priest and theologian Fr. Feeney will be regarded as a saint for his keeping the traditional teachings during a time when the Church heirarchy was trying to suppress our history and give the Catholic Church a more modern and worldly face.