The length of 718 production hinges upon when the replacement EV will be in production. Porsche say it will be introduced in 2025 but there’s little evidence yet of electric mules being out and about testing so they’ll need to get their skates on, and it’s just a guessing game ATM as to when the release could occur in 2025.
Another factor is how long it will take to rejig the production line(s) for the electric vehicle, although you can be sure that with a full order book Porsche will want to keep 718 production running for as long as possible. My guess is until the August 2024 shutdown which would provide a good opportunity to reconfigure the line(s), assuming the EV is production ready.
There’s an additional complication in that although the Cayman is built in Osnabrück, I believe that the 911, Cayman and Boxster are built on the same line(s) in Stuttgart and I’m not sure if an ICE/EV production mix is possible.
Jeff