Someone is going to ask during that earnings call, and Nintendo may be more forthcoming due to the new fiscal year, downplaying all non-Amiibo performance and focusing on potentially viable revenue streams. However, I doubt we'll hear anything major regarding NX. Maybe some mildly less cryptic hints. A review of the fiscal year just isn't the forum for these types of bombshell announcements. If anything, the most interesting bits would be regarding theme parks, movies, and even mobile instead of NX.
I think there's a possibility of a pre-E3 Nintendo Direct in May to go over the remaining games on 3DS and Wii U (e.g. Paper Mario: Color Splash), all of which will be at E3 but ultimately overshadowed by NX and Zelda, inevitably also on NX. I doubt we see games until E3. Any NX details between now and E3 will likely be mentioned in interviews, and it'll be things we expect yet will discuss and speculate to death about like partnerships with AMD and Broadcom. Manage your expectations. Outside of leaks, we're not seeing actual hardware and software until E3.
Assuming Nintendo absolutely launches NX this year, it hasn't had this quick of a turnaround between unveiling and launching hardware before. We live in a different time now. The spread of information is a lot easier, and judging by how much attention those fake leaks got, the hype is real. Apple has announced and launched a new product in less time. Granted, Nintendo isn't Apple, but point being, it can be done.