What if Germanic tribes never settled past their 750 B.C. borders? Would the Romans, assuming their empire isn't somehow butterflied away, settle Germania? Would the Celts? Red is 750 B.C.
There is no reason to stay there. Scandinavian terrain is absolute garbage for anything, and by the time coal and iron from there can be used meaningfully they would be talking all Slav and Celt and shit. I doubt they would go north around the gulf of bothinia probably because they think there is nothing there