I think arm abilities will probably be obtained in place of traditional dungeon items in TotK, but I hope this concept of Link's arm transforming returns in addition to rune-like abilities.
fThe super rich Japanese guy is very clearly going to be revealed as Norisuke Higashikata V, aka Joshu Higashikata, the eldest son of the Higashikata family and heir to the family company with Jobin passed away