What's interesting is that there are other potential ways this could go as well. It seems generally expected that these will release, and that they will be separate, $60 each. That doesn't mean they couldn't put together packages that offer a bit more for the price.
Twilight Princess, for instance, could include Link's Crossbow Training, which admittedly probably isn't enough to particularly register on most people's radar.
Wind Waker, however, would have an easier time with this by including the immediately Wind Waker-related game Phantom Hourglass and perhaps going further and including Spirit Tracks.
Perhaps it could even bring back the Tingle Tuner. I found the removal of the Tuner in Wind Waker HD, where the hardware was all included for the content to function without needing a separate console and cords, baffling.
Graphical touchups could be possible as well, though there's the question of how much time and budget would be put into that. I think a lot of people would appreciate a Twilight Princess where the stylization is tweaked, something more akin to the Wii U tech demo.
Wind Waker is a bit trickier here, considering it already received a moderately controversial graphical overhaul during its Wii U phase.
They certainly wouldn't have to just be straight ports.
Also, I assume Link can return to being left handed in these. That's also worth the price of admission.