Everyone always say's the best thing about mirrorless systems is you can put any manufacturers lenses on a mirrorless body because of the short flange length, but this is only an advantage to the consumer not the manufacturer. If the new body takes EF lenses natively by keeping the flange focal length the same and the RF lenses do indeed project into the body, like some older style Arri and Voigtlander glass, that would be an incredibly shrewd move on canons part, perhaps meaning that only EF and RF lenses could be used on the new body but also with an adaptor, possibly RF and already EF lenses, can be used on all the other companies mirrorless bodies. Canon then possibly protect their lens line, sell more lenses and bodies to people who own other systems and don't upset any of their pre-existing users who already have a lot of EF glass. It's not great for the consumer but it would be a very smart choice for a company. If it's all true however!