John Fredrick Parker
Donor
@vandevere I had been picturing Drusus succedding his father, but then Nero (son of Germanicus) succedding Drusus* circa 50 CE (spending the first few years of his reign at war with Parthia). Tiberius will certainly be more competent than OTL, and I imagine Drusus will mostly continue said competence; Nero Germanicus (or whoever succeeds Drusus) I'm less sure of (especially with the noted war as an x factor). That said, if we're right about Tiberius and his son, I imagine that adds at minimum another couple decades before the Principate reaches "Year of Four Emperors" level problems (so 69 CE at least delayed to 90, likely longer).
*son in law to Drusus as of our PoD
*son in law to Drusus as of our PoD