GiC's comment is spot-on; even things like dogmatizing the title "Theotokos" for the Virgin Mary have repercussions on our view of Christ - if she's not "Theotokos", then He's either not Theos, or He became Theos after birth, or something else.
Mary's assumption has no bearing on our doctrine of the Trinity. Since God alone receives our worship, our dogma has traditionally centered around what God has revealed about Himself. Changes in belief about Mary's assumption, conception, etc. only would have a bearing on our reverence of her, not on our worship of God.