According to Jim Murray, who works behind the scenes on The Expanse, Netflix have indicated they are not interested in continuing the series on their streaming service, despite already having the international airing rights. However, he also confirms that Amazon have shown an interest in picking up the slack.
Amazon already stream the show in the United States after the initial broadcast on SyFy. The show also arguably fits Amazon's original programming more than Netflix's. Amazon are on a major SF and fantasy binge, recently taking out options on the novels Ringworld, Snow Crash, Consider Phlebas and The Three-Body Problem, as well as developing new fantasy series based on the Dark Tower, Wheel of Time, Lord of the Rings and Conan the Barbarian series. The Expanse is also based on a best-selling SF book series and some fans have noted that the show's focus on (relatively) near-future Solar system colonisation even makes it a good fit for promoting Jeff Bezos's Blue Origins space project.
You can contact Amazon Studios directly here, using the "For Your Consideration" tab.