Er, is there any foundation for all this speculation?

I think the most I can agree to is that maybe Malladus is another incarnation of Demise's curse, now that Ganondorf is gone in that timeline. Spirit Tracks is one of the few Zelda games I haven't played, so I can't really say much on it. But I think that most of the stuff suggested in this thread is crackpot and kinda unlikely. Or at the very least, connecting Majora to it is very unlikely. Malladus and Demise may have some sort of connection, but brothers? Ehh, I dunno.

Also, if this is what you meant as a reasoning behind why you think Snowpeak is related to New Hyrule, I don't really see how this makes any connection there either.