A lot of the later German migrations had different causes though, didn't they? Like the birth of the Volga Germans, because Catherine the Great invited them, or a lot of the German populations in former Austria-Hungary which only started in the 18th century (aside from the older ones listed on that map). Danube Germans and Bukovina Germans were later than those, yet among the largest proportionately.
So with this in mind, you'd need more rulers willing to invite Germans to their land to settle. After all, they're industrious people, aren't they? You mention Poland, but having Germans settle the frontier to the south (the "Wild Fields" in nowadays Ukraine) against the Tatars and later the Turks might be interesting and plausible. Germans already were there to some degree OTL (later), but that seems a plausible outlet for early modern German colonisation.