So existing ambassadors will get 50 nights, correct? For the extra 50 nights (for total of 100 towards ambassador qualification) they need to spend US$14k which equates to US$280/night (excluding taxes and some charges). Normally it's 100 nights and $20k so $200/night.
So by reducing elite requirement by 50% for all members, ambassador would be the worst hit as our spend requirement per night increased from $200 to $280 (40% increase per night).