No way that thing is replacing the ST. Honda would lose all their sports-touring cred. Plus they'd lose out on all the cop bike variant sales of the full fairinged bike.
Baggers are real popular right now. Honda is probably just doing what they did with the Valkyrie 10 years ago. Take an existing bike, like the ST, or Goldwing in the Valkyrie's case, wrap it in some different Tupperware, and go after a different market segment. All the while keeping the original bikes in the line up.
Hondas Just trying to increase market share with minimal new investment like a new motor. Smart business move.