Since there hasn't been much change in religion from one or two millenia ago to today, then there also shouldn't be too much change from now to a few millenia from now.
Your first paragraph doesn't contradict what I said that much to me, since "one or two" includes both religions that were born over two millennia ago and ones that started between one and two millennia ago. Mormonism is a minor offshoot of Christianity. The dominance of the religions that you mentioned also began more than one millennium ago. I will grant that Sikhism is a newer major religion, but its level of influence just doesn't clear the bar for "much change in religion" for me quite yet.
It seems to me that the dissonance just boils down to semantics. The developments that you mentioned just didn't clear my bar for that "much change." The names themselves of temple Judaism and Rabbinic Judaism root them both in the same traditions, and the Reformation and enlightenment in general are just developments on the same core religious beliefs. Druidism, witchcraft, and Universalism just aren't that consequential in the world.
If I was trying to make a real point, it would have been that the baseline things that, as you said, stayed the same are more significant than the changes that did occur.
There's probably gonna be powerful syncretic movements in the African Pentecostal Church in a few hundred years once actual nations form identities and kind of sort themselves out. I'm sure we'll see new forms of Christianity there, if anywhere. China is gonna have to come up with something new, because having an officially atheist state holding onto nothing but Confucian Legalism as justification for the daily anguish of the state only works when the money they promise everyone keeps rolling in. Once they have a crisis and a big war they're probably gonna need a new philosophical and religious system drawing from any number of the 800 or so different religions they've had within their borders. It's happened before, and it's bound to happen again. They've already adopted "weird" western religions like Christianity and Communism in their drive to recover from the century of humiliation, lost faith in those, and now they'll probably do something new with any number and combination of eastern worldviews. They're pretty flexible for the most part because their oldest religion was also very flexible and their country has always had many of them simultaneously.