48b Surely, from now on all generations will call me blessed;
49 for the Mighty One has done great things for me,
and holy is his name.
This is God's work, not hers. That Mary will be called blessed is because God is working through her and her status (as a woman at that time) will be the highest because she is Mother of the Messiah.
All generations have and do call her blessed, for having that sure confidence and trust to say yes to God, and for being the God-Bearer (Theotokos).
And yet it all circles back to God. God is important here, not Mary’s blessedness. This isn’t a puffed up moment for her. She’s been thinking about this remember and she knows this for she praises God as mighty and that his name is holy.
The way ahead is scary: Joseph is in his rights to abandon her; her reputation would be shattered; she could end up on the very edges of society.
And yet this is a great thing God has done for her because it means the Messiah has come.
And so Mary praises God, she gives thanks. She trusts God to stay by her side, to never desert her in the rough times which are ahead.
(This is part of the Magnificat series during Advent...)