But seriously, I think the question is rooted in some odd assumptions about the nature of premodern religion. Any organized faith that emerges from Germanic paganism simply won't be recognized and won't recognize itself as Germanic paganism - it will recognize itself as something distinct, the way that Buddhists recognized themselves as distinct from Vedic Hinduism or Islam recognized itself as different from the Abrahamic faiths and Arab paganism. They didn't call themselves followers of the "Arab religion", and once their faith was understood, neither did their neighbors.
That in itself is a very odd assumption about premodern religion.
All religions change over time. The Sassanids believed they were following the one, true, unchanged Zoroastrian religion of Cyrus the Great. However not only was Cyrus the Great probably not a Zoroastrian*, but the Sassanids themselves made significant changes to the religion, creating a much more organized, hierarchical, political, and also less scriptural version of the faith. This caused a great deal of conflict with traditionalists who then formed a variety of splinter religions. The original Zoroastrianism itself undergoing even more change in response.
Much can be said about the evolution of Roman religion, which varied from a polytheistic pantheon very similar to that of the Greeks, to Neoplatonist and Stoicist influenced branches, foreign borrowed gods and goddesses, and the cult of Sol Invictus; yet all of these considered themselves the Roman religion.
Let alone the ecumenical councils in early Christianity, each creating a separatist church, with both the orthodox and separatist variants believing themselves closest to the original version of the religion. And following those councils, the East-West Schism creating separate Catholic and Orthodox churches both considering themselves universal and the true successor to the earliest Christians.
Any religion is going to change over time, and at every step, it will probably consider itself the same faith as before. Even with a holy text. But especially without one.
* We actually don't know the religion of Cyrus the Great, but his own records deem him a devout follower of the sun god Marduk. He may have been a contemporary of Zoroaster.