I honestly think its an absolutely terrible idea that the majority of the owners would be quick to say No to.
From a fan point of view, there is nothing more boring then knowing your exact draft position for the next 30 years.
Not to mention how many problems this would cause for small market teams the year they had the number 1 pick... Think wiggins doesn't stay an extra year to avoid spending the next 6 in Milwakuee?