Mary must certainly have passed away before John wrote his epistles. I think he would have mentioned it!
According to our Eastern Rite Catholics and Orthodox Christians, Mary did died, and when they went to her tomb, they could not find her body. It was a common agreement by the ECF that Mary was taken up by her son into heaven.
“If the Holy Virgin had died and was buried, her falling asleep would have been surrounded with honour, death would have found her pure, and her crown would have been a virginal one…Had she been martyred according to what is written: ‘Thine own soul a sword shall pierce’, then she would shine gloriously among the martyrs, and her holy body would have been declared blessed; for by her, did light come to the world."
Epiphanius, Panarion, 78:23 (A.D. 377).
“[T]he Apostles took up her body on a bier and placed it in a tomb; and they guarded it, expecting the Lord to come. And behold, again the Lord stood by them; and the holy body having been received, He commanded that it be taken in a cloud into paradise: where now, rejoined to the soul, [Mary] rejoices with the Lord’s chosen ones…” Gregory of Tours, Eight Books of Miracles, 1:4 (inter A.D. 575-593).
“As the most glorious Mother of Christ, our Savior and God and the giver of life and immortality, has been endowed with life by him, she has received an eternal incorruptibility of the body together with him who has raised her up from the tomb and has taken her up to himself in a way known only to him.” Modestus of Jerusalem, Encomium in dormitionnem Sanctissimae Dominae nostrae Deiparae semperque Virginis Mariae (PG 86-II,3306),(ante A.D. 634).
“It was fitting …that the most holy-body of Mary, God-bearing body, receptacle of God, divinised, incorruptible, illuminated by divine grace and full glory …should be entrusted to the earth for a little while and raised up to heaven in glory, with her soul pleasing to God.” Theoteknos of Livias, Homily on the Assumption (ante A.D. 650).
“You are she who, as it is written, appears in beauty, and your virginal body is all holy, all chaste, entirely the dwelling place of God, so that it is henceforth completely exempt from dissolution into dust. Though still human, it is changed into the heavenly life of incorruptibility, truly living and glorious, undamaged and sharing in perfect life.” Germanus of Constantinople, Sermon I (PG 98,346), (ante A.D. 733).
She is hardly mentioned after John the Baptist, baptizes Jesus. The ancient church knew nothing of the assumption. She was certainly a hero of the Faith, but not a central figure. She was not honored in the Hebrews hall of fame list of faith.
She was mentioned (Acts 1:12-26), and mentioned again and addressed as woman clothed with the sun in Revelation 12:1. Mary was also at the foot of the cross.
I just quoted the ECF that Mary assumed.