The brazilian Customs(Receita Federal) issued a new normative instruction saying that the TEMPORARY PERMIT IS NOT NECESSARY ANYMORE, yes, it seems strange but that´s how it is from now on.
Foreigners bikers or drivers are not the focus of the brazilian customs, it´s necessary a massive structure to control the borders against foreigners drivers and as "most of times" foreigners bikers or drivers don´t cause to much trouble, they decided to trust the you´ll definetly leave the country with your bike, car, truck, etc.
Another reason is that, selling a bike in Brazil is impossible once you can´t register it, of course you´re still able to sell to someone who will buy it to use in a farm or in a privae land, also you could leave your bike in Brazil for indeterminated period of time. But leaving the bike in Brazil still can be tricky, I say this because when you enter in brazil, they stamp your passport and give you a piece of paper with some details and there´s a space for the plate number, so I´m worried that when you leave the country they ask where´s the vehicle.
But in this case without the temporary permit the situation is much easier if you want to leave your bike for some reason in Brazil, you may have hundreds of excuses, you can say you came into Brazil in someone else´s car or in a bus once there´s no register of this vehicle, only the plate, it could be a bike, car, truck, bus, etc and now you´re leaving by without vechicle you came in. I even don´t think they will ask how you got in.
I still need to do some research about the possible consequences and I would be glad if you have questions so I can get the legal information straight from the customs and avoid problems to everyone. At the moment I´m storing some bikes at our hostel for people who will come back and others who left it for sale.
All the best