XCOM 2 was announced this morning, and is hitting in the Fall. 2K themselves refer to it as "Triple-A".
This might seem minor, but I don't think it's too similar a case because: this game was announced pre-E3, and Fallout 4 is an open-world RPG, which will most likely have a much higher budget (and general level of mainstream anticipation) than XCOM 2.
It's a good example, though, but I really don't think it's that comparable to a Fallout 4. And don't get me wrong: I prefer shorter turnaround times for game announcements to release—and, hey, maybe it's even better when it comes to sales performance and hype—but I really, really don't see this happening with a game like Fallout 4. I am 100% convinced that it can't happen; I see anything else as simply hoping it would happen.