Guarantees
Dave - sadly the guarantee you are looking for cannot exisit.
No CEO can guarantee what you are asking. Scale it down, if you owned a sweet shop and employed 5 people at £100 per week - could you really guarantee, that whatever happened to the sweet market in general, the fact another bigger, cheaper sweet shop opened next door, the facts kids didn't want to buy sweets anymore (!?) - you would always faithfully employee your 5 people at £100 a week right up until the time that the debt collectors dragged you out of the shop as your liabilities were in excess of your assets?