You can already import a 6-channel file (assumed to be 5.1 format), which will be split up into separate files in the montage and can be edited there as a group, though somewhat tediously - using the Alt key to make some actions operate on all selected clips. Functions only available in edit view you cannot use, of course. You can then render into 6-channel files again, split up into songs if you like.
Although you can even now render montages with other numbers of channels into multi-channel files, you can still only import 6-channel ones (which is a big limitation for me, as I work entirely with 4-channel files). I am hoping (following some hints) that this anomaly has not been addressed because true multi-channel file handling and editing really is just over the horizon at long last. It is reasonable to assume that the capability of writing multichannel files from parts of a montage which already exists will not be lost in WL10.