There is no way to avoid line ending normalization, nor will there be in the future. Support may be added to preserve CR characters, but this isn't the same thing as supporting mixed line endings: CR characters would appear as actual characters in the buffer.
Mixed lined endings are something that is going to create issues for many tools. For example, many unix tools won't handle it, and compiling code with mixed line endings in Visual C++ on Windows will result in incorrect line numbers in error messages.