Credit for the discovery goes to this InstallBase thread,
One thing I like to do from time to time is to check on trademarks. There have been instances where a trademark filing has indicated a new game announcement in the future, two instances I can remember was when Capcom trademarked Ghosts n' Goblins before they announced the resurrection title and...
www.installbaseforum.com
but alongside the trademarks of names for many announced titles for GB / GBA NSO, there are three that have
not yet been announced:
1) The Sacred Stones - The least interesting of this selection, since it was naturally going to be coming down the road eventually; already being localised and available on Wii U Virtual Console. Good thing Fire Emblem fans have something else to look forward to...
2) Solar Striker - A first-party Game Boy title that isn't often talked about; a rare vertical scrolling shoot 'em up attempt from Nintendo. This game entirely skipped 3DS Virtual Console, so showing up on NSO would make for a notable addition.
3) The Binding Blade... in English?! - Don't get it twisted either, this trademark, like the others, is fully registered for use outside of Japan (see below). FE6 was announced for release on the Japanese GBA app, but obviously wasn't for the international app given it has no existing localisation. This, registered at the same time as other titles already part of the GB/GBA NSO slate, may perhaps suggest that an official localisation of FE6 is on the way? Can't make that claim with certainty, but it is a very strong clue towards that being the case, and has massive implications for the future of NSO if it comes to pass.