I've always been interested in a consolidation of the old prussians. Believe it or not, it was actually a bit easier than you'd believe. They even had their own quasi high-king figure, with a decent amount more respect than their irish counterparts, called a Krīvu Kirvaits, I believe.
The krivu kirvaits was seen as a sort of..pontifical figure, I suppose, would be the best estimate. He was elected, and allegedly had the ability to communicate between gods and men, and to my knowledge was generally seen as divine. He's mentioned in a couple texts that I've found, and apparently the krivu kirvs (an alternate name) was written about by contemporary figures like Peter of Duisburg, a teutonic scholar. He had dominion (not sure that's the proper word, but meh.) over not only the old prussians, but their neighbours, according to peter. He also stayed in a specific holy place, referred to as Ramava, which was used as not only the singular place to hold sacrifices, but for secular meetings between the leaders of the "Tautos", or the regions each tribe resided in. These could be of a political, religous, or on occasion, military nature.
Although peter did have some bias (oddly enough, on the side of the old prussians!), his information on the subject seems to be, mostly, reliable.
Had the old prussians been a little more lucky, and had elected a single military commander for their armies (let's say Herkus Monte, who clearly would've been the most capable military leader, as he's an almost arminius-like figure), the knights might well would've been wiped out or atleast kicked out of prussia, allowing the prussian tribes to consolidate.
An earlier timeline would simply require a sort of "great man figure" being the krivu kirvaits, but where's the fun in that?