The obligation to buy will mean that we've already agreed a contract and wage with him upon promotion.
I'd imagine that if we don't get promoted, no such agreement is in place, and so we'd need to negotiate a new salary which one would guess would need to be quite a bit less.
I'd imagine that if we don't get promoted, no such agreement is in place, and so we'd need to negotiate a new salary which one would guess would need to be quite a bit less.