the lower power is compensated for by the extra traction points on a 6 axle loco.hence my equation that you can get the same pulling power as 2*cl86.There are still some points on the network which require either co-co or 2*bo-bo haulage.
As for the improvements in battery technology,I wholeheartedly agree,but at present it is by no means a panacea. Up there in sky -fairy land we could use miniature thorium reactors as power plants,negating the need for any fossil fuel or overhead wires, but that is a long,long,long way off.
My take is that there is no prospect of the leasing company handicapping their loco under electric just so that it can have more power under diesel/battery. Besides, your argument strikes me as rather contradictory.
Your suggestion the loco ought to have six axles because it will have the same "pulling power" as a pair of class 86 locos. Actually on an electric mainline it is power output that will allow your train to keep schedule and fit in around other fast traffic. Nobody in their right mind is going to build an electric loco - and a six axle one at that - with rated power output not all that much greater than a four axle class 68. That belongs - to borrow your expression - in "sky fairy land". Not when high power under electric is so easy you might as well do it whether you need it or not. Even a three car class 755 has 2.6MW under electric.
The contradiction is that, if power output is dismissed as less relevant than number of driven axles under electric, why does high power suddenly become important for non electrified lines? Modern power electronics mean that the full "pulling power" of the loco can be exploited under relatively modest diesel or battery power to get the train moving, and the traffic on non-electrified lines will be less demanding of train performance.
These are fast mainline goods locos, and our network is progressively being electrified, negating the features you insist the engines need. Unless there is a major intermodal terminal in Pwthelli I don't know about, for which your proposed design, with high number of axles to spread the load over the Barmouth Bridge and good diesel power to get it over the Cambrian mountains, would be ideal.