Your post above wrote “the location of the proto-Germanic speakers”. Terminology matters; Proto-Germanic is something strictly defined as to what it was, with a longstanding consensus about where and when it was. If you wanted to talk about pre-Proto-Germanic speakers (or “Paleo-Germanic” speakers as this paper does, though I suspect some would quibble with that term used for a very early date), then you could have done so.
Moreover, you posted about a “new theory”, but the paper here only gives new evidence for an old theory.
Moreover, you posted about a “new theory”, but the paper here only gives new evidence for an old theory.