Holding down the bottom button would provide a ``shuffle this playlist'' option in addition to the options currently provided.

If this gets implemented, can we also get an "Insert Sequential" option on that menu, too?

I'd love to be able to insert a sequential album (or playlist) into my big down-down-down random shuffle without having to turn off shuffle first.

That option would only need to be visible if (a) shuffle mode is already on, and, (b) you have selected a multiple-track playlist rather than a single track.