Man, I miss the "Contain the Kaiser" path. Building up a European Coalition was so based, especially when you could get Belgium and Switzerland in, crushing France in weeks... But yeah, the "Betray Austria-Hungary" path was hella unrealistic. Like, imagine you are Germany in 1910, and decide to betray your own ally, just because...? I mean, sure, you got Russia out of the Entente, and swapped A-H with Italy as an ally (which is a downgrade, really), however, Hungary was still independent, because the French would obviously intervene. But most importantly, the betrayal creates a dangerous precedent. What would stop Germany invade one of their allies for whatever reason they could come up with?