When it comes to NX power, another thing to consider is Nintendo's history of console power consumption, & going off that, NX is guaranteed to consume under 50 watts.
Then you have to consider the fabrication process node...will Nintendo go with 14/16 nm, or 22/28 nm? The 14nm Zen apu by AMD would give Nintendo great performance per watt but may be costly. If they go with the more mature node, don't expect a big jump.