Steps (new)630wh Vs 504wh external battery wild speculation
Larger? Definitely
Longer? doubtful
wider? doubtful
taller? if pics are to be believed, almost certainly
Heavier? Absolutely. reportedly by a whopping 900g
How are shimano most likely to have likely gone about increasing capacity?
Here's the internals of a 504wh battery
in all likelyhood and as seen by promo pics Shimano would seem to have gone the route of adding more cells to their existing design. And from the taller looking new battery casing it would seem likely they have added a full row of cells below the bottom row of the previous design.
It stands to reason a taller heavier battery will need stronger more secure/stable mounting hardware and we know the new battery requires exactly this.
Most current E7000/8000 external battery Emtbs do actually have enough clearance above the battery to accomodate a slightly taller battery. Whether that new mount will be able to be swapped with the original 504wh mount is yet to be answered. But I can see why Shimano would not be keen disclose this information at the present time.
it is also yet to be answered whether the new mount can still accomodate the older batteries.
Shimano do seem to be doing a pretty decent job of retaining a level of backwards compatibility across their cycle range ATM, particularly the product releases just anounced and due for release towards the end of the year.
My advice: Be patient... But don't hang about waiting! Life's too short.
Disclaimer: almost a kilo of extra weight for 126wh isn't even something I'm interested in, nevermind the gamechanger so many seem to see it as.