So many have been mentioned already. New versions of Yeti arc-x, Trek Stache, Cotic Soul would all be greeted with excitement.
A couple of others:
Bring back the Trek 69er or Singular Hummingbird – mullet 27.5/29 with short dual crown fork and updated geo
Yeti world cup xc race bike
An affordable/accessible version of Andrew’s Waltworks
A full suspension tandem with modern geo and e-bike components for durability – we’re genuinely looking for this as our 26″ Ventana feels quite old school