Ok, between LNBA and nowadays there is no major shift in Germanic genetics but Nordic LNBA dates back to 1,600 BC, almost 1,000 years after the earliest mentions of ancient Gutians in the Mespotamian sources, from another side, we know the original land of Germanic people, as an Indo-European people, was in Iran, so even in your theory it is certainly possible that Goths, Germans, ... came from Iran. If we assume that your theory is correct, it can be said about my theory that in the 1st millennium bc Germanic people still lived in Iran.