mike700 is exactly right the money they attract to the uk is huge and as he says getting rid off them wouldnt necessarily save much if anything as most of the royal residences would still have to be maintained plus the cost of replacing them with a president or what ever. you can bet they wouldnt be cheaper.
i am in favour of charles plans to streamline things esp sidelining andrew who is a disaster. ive met and even worked with many of the royal family at various times during my 20 years in the military and i have to say i am a huge fan of anne who must be the hardest working one out there and definately takes after her father and doesnt suffer fools, i bet she gave andrew short shrift i would have loved to be a fly on the wall that day.
plus the duchy of cornwall contributes loads now in taxes and contributes in other ways the country could lose that as william or whoever could adopt the attitude of reducing his tax liabilities in a variety of ways.