1. Simultaneous development: Saw 8 (Jigsaw), the latest installment in the Saw franchise, was being developed simultaneously with the potential sequel to Saw 7 (Saw 3D: The Final Chapter). As a result, the rights holders chose to release Jigsaw instead of Saw 8 initially.
2. High profitability: Despite mixed reviews, the Saw films have proven to be highly profitable at the box office, and Jigsaw was no exception. It earned over $100 million worldwide on a budget of just $10 million, making it an easy decision for the studio to greenlight more sequels.
3. Fan demand: Despite being marketed as "The Final Chapter," Saw 7 left open the possibility of future installments. Fans of the series continued to demand more, and the success of Jigsaw showed that there was still a strong audience for the franchise.
4. Creative possibilities: The Saw franchise has always been known for its intricate and twisted plot twists and puzzles, leaving open the possibility for new storylines and characters to be introduced. This gives the filmmakers and writers plenty of creative freedom when it comes to developing new ideas for future sequels.
5. Legacy characters: Although the titular character of Jigsaw (John Kramer) died in Saw 3, his legacy and influence on other characters have continued throughout the series. This allows for new perspectives and storylines to be explored even without Kramer's direct involvement.
6. Franchise revival trend: The late 2010s saw a trend in Hollywood of reviving long-dormant franchises, such as Jurassic Park, Star Wars, and Halloween. The success of these revivals likely influenced the decision to continue the Saw franchise with Jigsaw and beyond.
Overall, it's a combination of factors that led to the return of the Saw franchise with Jigsaw and the potential for future sequels. Despite early marketing suggesting that Saw 7 would be the final chapter, the continued profitability and fan demand for more Saw films made it an easy decision for the rights holders to bring the franchise back from the dead.