[spoiler:1wavi8dz]Sanderson said that if he would write new mistborn books, they'd be set far in the future, in a industrial-like-age, where there would be no mistborn anymore but there'd be all kinds of mistings, including these that were not used in this triology[/spoiler:1wavi8dz]
[spoiler:pdcxf189]Marsh survived, he(aka Ruin) killed Elend at the end. Since he has a stockpile of atium and he is essentially immortal, at least until he runs out of atium. Brandon said he may use him if he writes future mistborn books.[/spoiler:pdcxf189]