A proper continuation after T2 would have been a backstory film showing in the beginning Skynet being developed and then becoming self-aware launching nukes to Russia and then Russia retaliating by launching nukes to the US.

The few human survivors that are left are gathered up by the machines to work in camps branded by laserscan. John Connor saves the humans from the camps and they form the human resistance with John Connor being their leader teaching them how to fight back against the machines.

The war rages on for years until near the end, as depicted in the draft of the original opening to T2, the resistance smashes Skynets defense grid and the machines become inactive winning the war for them but as a last ditch effort Skynet sends back two terminators

The resistance learns of this and capture’s the lab complex with the time displacement equipment and after Kyle Reese “volunteers” and is ready to go through John tells him to give his mother a message for him (as depicted in T1). After Reese is sent back John finds the room with the unactivated terminators and see’s the one from T2.