Short answer - yes.
Extended answer - For us, it's a combination of kids getting older and divided/blended families. Since my stepkids swap holidays on odd/even years according to their parents' custody agreement - this year, Dad has them for Thanksgiving Day and Christmas Day, Mom has them for Christmas Eve - things aren't constant from one year to the next. This year, we've tweaked it even more, since Grandma is coming to our place on Christmas Day instead of us going to hers.
Now that my son is out of university and working/living on his own, I'm not assuming he'll be with me every Christmas. This year he will be, and he's bringing his girlfriend (they spent Thanksgiving with her family, and he's not even seeing his dad over the holidays), but who knows where his life will be next year? I try not to take anything for granted.
Since my stepkids make the move from one parent to the other on Christmas morning, gift-opening at our house happens either very early or not till mid-morning. My husband's family does stockings for everyone (but they're from Santa - oops, I almost forgot!), and that's new to me. My side of the family spends Christmas Eve at my sister's, and my nephews will have to get used to their step-cousins only being part of that every other year.
Yes, it's definitely evolving. MaryP, your Christmas-morning tradition with your kids sounds lovely; I'd get wistful about that changing too!