Personally I hope they never impose such an awkward naming convention.
However, what about the problems that BEM tries to solve? Using a naming pattern to communicate structure (element E is a "child" of block B) is a good idea (instead of e.g. a descendant or a child selector) because of:
a) Performance: one class (e.g .blockB__elementE) will be faster to "match" by the browser than .blockB > .elementE /.blockB .elementE;
b) Less coupling to DOM structure: to have the desired style, element E doesn't necessarily have to a child of B.
Similar points can be applied to modifiers. A "btn--large" instead of "btn btn-large" seems like a good idea for performance and also to avoid conflicts (the latter class will override the first, but I wouldn't want to care with order).
I spent a lot of time deleting stuff lol. Still more to optimize around though as we work through the alphas.