Purvis and Wade's Script: Shatterhand
Last summer, before Boyle and Hodge boarded Bond 25, a rumor emerged that the movie would be called Shatterhand and would be based on the 2001 Bond novel Never Dream of Dying (by Ray Benson). In that novel, Bond is tangling with a criminal group called the Union and trying to track down their leader, a blind supervillain called Le Gérant. The rumor also claimed that both Christoph Waltz and Dave Bautista would reprise their Spectre roles as Ernst Stavro Blofeld and Mr. Hinx, respectively. Waltz later dismissed rumors of his return, saying, "No, I'm sorry. I'm really sad, but that's the tradition, that there is a new... name. Sorry. I would've liked to" - though this may have been a reference to Eon looking for a new script. Bautista said in April 2017 that if Craig returned as Bond, there was a chance that Hinx would be back as well.
Now it seems that not only was last year's rumor accurate (at least in part), the Shatterhand script is now back in play. The August 30, 2018 issue of Production Weekly lists Bond 25 as being developed under the working title Shatterhand, so Eon presumably wants Vallée (or another director, if those talks fall through) to bring Purvis and Wade's story to the big screen, rather than coming up with a story of his own.
According to the rumor from last year, the Shatterhand script draws not only on Never Dream of Dying, but also on the earlier films You Only Live Twice and On Her Majesty's Secret Service, which featured Blofeld as the villain. In Ian Fleming's novel You Only Live Twice, Blofeld uses the alias Dr. Guntram Shatterhand, which would explain the movie's working title. It certainly makes sense that a movie based on Never Dream of Dying wouldn't exactly follow the novel, since the novel is the third in a trilogy and begins with Bond already having faced off against the Union twice. It's possible that, for simplicity's sake and to continue the plot threads set up in the previous movie, the Union has been substituted with SPECTRE in Shatterhand, and that the villain will be Blofeld rather than Le Gérant
The real clues about Shatterhand's story likely won't begin to emerge until the film begins casting. If Bond 25 really is based on Never Dream of Dying, our next Bond girl will be Tylyn Mignonne, a French actress who is married to a film director with connections to the Union, so look out for news of the movie casting an up-and-coming French star. It also wouldn't be surprising if we learned that Waltz will be returning after all, along with Bautista (whose schedule has recently been cleared due to Guardians of the Galaxy 3 being delayed indefinitely).
The Craig era of Bond has had mixed success, with Casino Royale and Skyfall receiving widespread critical acclaim, but Quantum of Solace and Spectre regarded as rather mediocre entries. Many felt that Boyle was an interesting choice of director who could mix things up by bringing his own vision to the franchise, but it could be argued that the final film of the Craig era isn't the best place to bring in a totally new vision and introduce a new villain. For the sake of narrative and tonal consistency (Purvis and Wade have, after all, written every Craig movie) and potentially giving Waltz's Blofeld another chance, perhaps it's for the best that the studio has returned to the original script.