A brushed motor with rare earth will smoke any brushless, hell they already smoke them with ceramic magnets, only to blow up because of design/pricing limitations. Yes they will need design changes, but not major ones and they will benefit from better magnets even without modifications, just not as much as they could.
No offense taken 
...but you need to ask your self...where do I get this stuff I post here? I get it by talking to Rick Hohwart, Sean Cochran, Oscar Jansen, Bob Novak, Ernie Provetti, etc.....
With all due respect, where have you heard that a rare earth BR motor will smoke a BL seeing as there are none in existance right now that run appropriately in r/c cars?
And before you say anything else, the proposal was put in by a complete privateer so no manufacturer involved, the idea is to put brushed and brushless on a similar level as far as magnets are concerned and may the fastest/more reliable design win, as right now, none are reliable anymore. Brushed blow up and brushless blow up or shut down.
What sanctioning body are you talkling about ROAR, BRCA or EFRA? The ROAR proposal did not come from a privateer. I know, I am on the ROAR ExCom
So why would sagami refuse to put rare earth magnets in their cans, surely TOP are a big enough customer of them, especially as if brushless take over the market, sagami will be losing a lot of turnover...
Becuase there are things they just refuse to do. Ever wonder why there is no Reedy Stock motor? How about ROAR legal 19T motor from some one other than Trinity? Sagami refused to make the Reedy motor that Reedy wanted and they say they cannot make a motor in accordance to ROAR 19T rules. Why, who knows...they just say they can't (or won't) and Reedy and Orion do not have the ability to go somewhere else. Why, because only Sagami and TokyoMec have acess to the good TDK magents we use. Becuase of this they will probably be resistant to making rare earth motors with commonly available Neo magnets. They have the market cornered and they will not want to mess that up.
B/L will be the future only if brushed aren't given the means to go forward, and this starts with allowing rare earth
This is a bit silly. No matter what BR motors are created they will still need to be rebrushed, comms will need to be cut, maintenece will always be more than a BL. This is not what racers want..heck most guys dont even maintain their cars properly!