Next major update is 1.4.5, or 1.5 if they call it that. The big one they've been working on for years.

Resolves based on the a Wikipedia page or Re-Logic's self-reporting.

They don't need to actually release the numbers within 2 years of that update's release, if they release it a good chunk later but it still seems like they would've passed the threshold in time this will resolve YES.

Terraria is currently at 64 million sales. For reference, when 1.4 released, it went from 30 million to 44.5 million in about two years.