On the BBC One Show they were interviewed in the wake of Sum Of The Parts/RKive. When asked about possible future release of any unheard material Banks gave a very definite "No". When pressed on it he said "I'm the band's archivist and I'm telling you there is absolutely nothing left to release".
That's very telling as it shows that he, and therefore they, don't regard anything in their vault as worthy of commercial release. We all know there is stuff so he doesnt literally mean it's EMPTY but clearly he means what is there isn't releasable. Barring the slight blip of this BBC set, which isn't a significant reversal of Banks's comment.