Yeah, FLAC is fixed point only, but since there is a variety of open lossless formats to choose from, everyone should be able to find something that suits them best.
BTW: As long as there is no clipping, it doesn't really matter if you use floating point or not. The only advantage of floating point over fixed point is during production, as you can avoid clipping when routing audio through various plugins/etc.... However there is really no difference when dealing with normalized files. Afterall, a 32-bit floating point PCM signal has the same SQNR ratio as a 24-bit fixed point PCM signal (because the mantissa of 32-bit floating point numbers happens to be 24 bits wide).