I have a pretty good feeling about a reveal on March. Given the drip-feed of information coming from Nintendo in regards to announcements and updates, I'm not expecting more than one reveal around E3. Instead, we'll get our next character within March/April, then the following one around June/July, and finally around October/November.
The only alternative is waiting 5-6 months from here on out if the next characters warrant reveals side-by-side, and that would be the most favorable outcome if we want the 5chan leak with Crash/KOS-MOS/Reimu to be true. After all, what better opportunity is there to announce Eastern and Western appeal reps than a big event like E3? It'd basically be Hero & Banjo New Game Plus.
While it's not impossible to get Reimu and Crash at separate points throughout this year, it just seems unlikely, especially since it'd probably make more sense to plan ahead and not announce characters in such an order that it'll annoy and confuse a bunch of Smash fans. Best case scenario, Crash/Reimu dual reveal with Kosy as the final character, while the worst case scenario is Kosy in March, then Crash in E3, and then Reimu as the final character.
Bear in mind, this is just a hypothetical in how the scenario of the 5chan leak could play out if true, but since there is no solid proof that it's legitimate apart from either really lucky guesses or a disgruntled employee (that hasn't been caught yet), I'm on the boat that no one should have this kind of information. The only way things could be different is if there is a similar vault breach in the DLC project to the Capcom fiasco that might have went under the radar.
But then what are the odds of that? Anyone dumb enough to pull off that stunt would have to at least know that Nintendo is more than capable of tracking them down, so rather than pulling the ramson card for money, this theoretical employee or insider would have to lay low with no real benefit other than seeing how the internet would react once they start piecing the announcements and timeline together.