Ah, I thought you meant something like this…
… which would be neat, too 
If I understand you correctly, you mean e.g. having one track with a single long sample playing, and when you’re working on the middle of the song and press play that sample starts where it would be if the song had played normally to that position? That would be very useful indeed!
That’s exactly what I meant with audio tracks, and the picture you posted is exactly what I meant with FX automation 
In audio track it should be somehow linked to wave clips, while in patterns it could be used as an alternative view to the bottom automation window, so we could have selected envelopes always visible directly in the pattern editor.
i have been waiting for this for ages in a tracker… especially doing tracks with vocals … too many 9xx commands = headache