She did die, but she was not corrupted. We know that after the Crucifixion Mary was cared for by the apostle John (John 19:26-27). Early Christian writings say John went to live at Ephesus and that Mary accompanied him. There is some dispute about where she ended her life; perhaps there, perhaps back at Jerusalem. Neither those cities nor any other claimed her remains, though there are claims about possessing her (temporary) tomb. And why did no city claim the bones of Mary? Apparently because there weren't any bones to claim and people knew it.
I mention this because in the early Christian centuries relics of saints were jealously guarded, highly prized. The bones of those martyred in the Coliseum, for instance, were quickly gathered up and preserved; there are many accounts of this in the biographies of those who gave their lives for the faith. Yet here was Mary, certainly the most privileged all the saints, certainly the most saintly, but we have no record of her bodily remains being venerated anywhere.
The evidence for the of the Assumption, as understood and explained over the centuries by the Fathers and Doctors of the Church, concern not so much scriptural references (there are none that speak even indirectly to the matter of Mary's Assumption, and only a few that deal with the subject of assumptions in general), but rather the fittingness of the privilege. The speculative grounds considered include Mary's freedom from sin, her Motherhood of God, her perpetual virginity, and--the key--her participation in the salvific work of Christ. It seems most fitting that she should attain the full fruit of the Redemption, which is the glorification of the soul and body.
The trouble is that the movement in the Latin church to declare the fact of her assumption as a solemn dogma included many who denied her death, and the solemn dogmatization your confession formulated was deliberately ambiguous on the point, leaving her assumption after death or assumption before death as a matter for private opinion. The coupling of the unnecessary dogma of the IC of the BVM with the assumption before death opinion seems to me to be heretical, though as a humble subdeacon I am in no position to propose new anathemas.
That's the consensus, but the dogma promulgated in 1950 allows for the possibility that Mary didn't die and was assumed like Enoch and Elijah.