Burgundy or Pilsner?
Basically I could see two points that might work.
Burgundy survives and retains medium-power status post-1477. In the course of the 16th century it experiences its own Reformation, becomes Calvinist (if Calvin exists...) anmd increasingly finds its southern flanks impoverished and sidelined while the economic and political center of gravity shifts to Flanders and Holland. The trilingual (northern French dialects, Flemish-Dutch and Low German) state encompassing most of the Rhineland, the Saar, Moselle, Franche-Comté, the Netherlands, parts of Frisia, and modern Belgium is then just big enough to suistain a colonial Empire...
Or:
The Catholic troops are routed in the Battle of the White Mountain thanks to more decided Dutch and English support and fewer morons in command. Bohemia goes Calvinist, as do large swathes of Central Germany at the end of a savage nine-year war in which the Dutch Army of Prince Maurice of Nassau takes decisive part. Germany is religiously divided three ways: a Lutheran North and Northeast (Prussia, Northern Hanover, Frisia, Schleswig-Holstein, Mecklenburg, Pomerania, and the Hanseatic cities) under Swedish hegemony, a Catholic South (Bavaria, Austria, Franconia, the Palatinate, and the border states to France) and a Calvinist Center (Hesse, the Rhineland, Brandenburg, Saxony - though I'm dubious about that last one). The South becomes the battleground between Austria (much weakened in the war, but still a serious power) and France whilwe the center orients itself more and more towards its hegemonial power, the Netherlands. A succession of dynastic marriages put Brandenburg, Brunswick and Hesse into personal union with the Netherlands (after some fiddling with succession laws). In the course of the 18th century, this patchwork is built into this ATL's German hegemon, governed from Amsterdam (no need for a 'king in Prussia' construct as the royal crown already exists outside the Empire). With the troop reservoir and enough continental muscle to keep the French off their back, the Dutch can exploit their colonial possibilities far more ruthlessly. Russia, meanwhile, becomes a Vasa client state and eventually disintegrates under the political weight of Poland and Sweden, leaving Central Asia and Siberia a colonial 'no-man's-land' until the 1800s, when Britain and Persia clash on the steppes and China faces redoats on the Amur frontier...
Admittedly, very unlikely. But I like it.