No doubt people are still wondering where Hilbert went to setch for his friend. Many speculated he would make anapperance in BW2. But maybe, this is it, this will be Hilbert's return. Maybe Hilbert will be the new Red. Or wannabe Red depending how much you're obsessed with Red. Think about it. No one knows where Hilbert is? A different region? It could be this one. You couldn't battle Red until 1 generation later, in a different region. Hilbert could do this. People theorize a connection to this region and Unova. Maybe this region will be like Johto, where you visit Unova. I know I shouldn't be jumping the shark but COME ON Unova has planes, trains,
automobilesships. Even if there isn't a visit to Unova on a system as powerful as the 3ds, I think Hilbert really should return to put an end to the N saga. Perhaps towards post game they'll be dialouge such as "you remind me or a someone...that look in your eyes...." or "Sigh....I'm so lonely, separated from my pokémon while they are in the daycare, it kind of reminds me of that boy I met, looking for his friend", you know slight forshadowing Hilbert has been in the region. And then, in some random cave/mountain/forest, perhaps we'll finally find Hilbert and be able to battle him like Red and Steven.
Now to recap, these are the reasons I think it could be true
Similarities to Red, such as dissapeaeing after the leauge, going to a different region that's introduced next generation (technichlly Mt. Silver is between Kanto and Johto but the map says Johto).
This region is likely connected in some way to Unova like Johto and Kanto.
Hilbert's story hasn't been fully resolved.
The way people talk about him in BW2 is as if he's some legendary hero, the way people refrence Red.
And finally, Hilbert (and Hilda I guess because I just noticed this might be sexist) had no apperance in BW2, which is kinda weird.
And just for the funs if (s)he is battleable.
(Don't worry there all event pokémon, gifts or inevitablly battled)