One good 'Dr Stone Naruto fanfiction' could be one where Naruto is transported to the Dr Stone world. He might use his ninja skills in a world full of science. For example, his shadow clone jutsu could be used in interesting ways for tasks like gathering resources or helping with scientific experiments.
At the moment, there's no definite information about more Dr Stone manga. It could happen if there's enough demand and the creative team is up for it. We'll just have to wait and see.
It's hard to say for sure. The decision often depends on various factors like the popularity and sales of the original series, as well as the author's plans and the publisher's strategy.