This is something Logic has, a "No Output" track. Basically this is a zero-overhead track that allows you to store clips and bits of arrangement without deleting. For example, say I want to experiment with the arrangement (in the arrange view) and try other clip combinations or fancy cut-pasting of clips, i'll typically drag the existing time-region clips onto a "No Output" track (usually created adjacent to the active track), then, experiment with other arrangements in that time-region. It a good place to store older ideas, particularly in the arrange view.
Using a Logic example [see image below], the "No Output" track contains the original arrangement ideas for the "Audio 5" track. The "No Output" track allows me to store complex bits of arrangement to be used again, here or elsewhere in the arrangement. Live could use a similar approach. "No Output" tracks in Live's arrange view can be absent in the session view. The key here is that these tracks represent virtually no audio i/o overhead, they're just storage regions.
