Maybe. Though I'm of conflicting ideas of what to do with Courland - run into an interesting idea (an abandoned mini-TL on Russian AH board). Involves first wife of Friedrich Casimir of Courland dying in 1778 of something ranging from childbirth to smallpox, and Sophia of Russia getting into conflict with her brother Feodor III, among which the idea arises to marry her to widowed Duke of Courland.
After the religious issues are settled (marriage of Magnus of Livonia to Maria of Staritsa is taken as precedent), Sophia leaves for Mitau (she is allowed to keep her faith, though her children are to be raised Protestant (with possibility of one of her children coming to Moscow to be raised in orthodox faith). Though Feodor III likely dies as OTL, the removal of Sophia from Russian political scene causes great butterflies for eventual Petrine reign, and Russia gets earlier access to Baltics via Courland.
I plan on Joseph having a son, though whether he dies on schedule or not is up in the air.
Oh that sounds fascinating, and possible way for Peter to get Russia onto the stage much earlier.
And alright interesting. Would Charles be relegated to a simple Archduke then?