y'all some heartless bastards. ofc Shin isn't dying, but you can say the same about Luffy or Meliodas or Tanjiro or Deku or any other protagonist. At the worst, they'll go into a comatose state and we'll have to spend an arc reviving them or something. Just appreciate the emotion for what it is in the moment, the other characters don't know Shin will survive!
Shin "dying" from exhaustion and wounds is the appropriate consequence of expending everything he had to defeat Houken. The question now, is will Kyoukai have to give her life to revive him? Or will there be some other method?