Agents known as Shatter and Crusader will probably never appear in Valorant. While the community had found some leaks, it seems they ultimately lead nowhere. Riot Games has put an end to speculation by specifying that these two agents are projects that were put aside during the development of the game.
Datamineurs are constantly searching the game files for new content. Whether it's skins or new agents, it's a race for information and scoops.
Riot Morello, Valorant character design lead, was adamant about the so-called new Shatter and Crusader agents: they're abandoned plans that won't be released. As in every game development process, there are a lot of tests and some projects aren't selected in the final version.