Would it be the case that a lower grade or even waste silicon blanks can be used to do the power component?

Can a lower level of 'scale' be used, to achieve the power lines, and so more assured/fault-tolerant production?

If it has to lock-step the generational burdens of masking and technology, and is unable to capitalise otherwise unused silicon, it doubles costs in those inputs. Not that it doesn't mean it can't deliver both improved power budget and better signals (less interference) but it might even be capable of becoming a lower cost option, if the bonding/positioning/lapping processes aren't too expensive, and its input costs and consequences for wiring plane costs are better than the alternatives to boot!