Why would it get scrapped? Mine is almost unusable with watchOS 4 so I hope it won’t get any further updates which render it then completely useless.
The First generation Apple Watch will likely not see support for watchOS 5. The processor lags as it is in watchOS 4 and will likely be the last version. Figuratively speaking, that would have been three years of updates for the Apple Watch first generation if it is not supported through watchOS 5.