What is the length of the hot end?
The normal volcano hot ends are 21mm end to end, the picture on the listing says 10mm for the threads.
Also will hardened hot ends be available for sale after launch?
This is something i kind of dislike the 3D-Printing community for. The leak of standardisation. Well, of course, there are alway a lot of changes but, why not even try?
At this point i whould like try to establishing a Nozzle-Norm. 
ND04FD175M6x16SW7
looks complicated but its:
Nozzle Diameter 0,4
Filament Diameter 1,75
Thread M6
Thread length 16 mm
Schlüsselweite 7 mm (Wrench size)
Beside special nozzles like the Revo, all Nozzles have the upper values.
Everything else can be described in the marketing name.
The nozzle who came with the normal SV06 whould be. ND04FD175M6x7SW6
And the new one will be sure a ND04FD175M6x16SW6
It whould be possible tho shorten it to 04175M616W6 but i think the longer version is easier to remember and to read.
So, if you go out there and finde a FD175M6x16 nozzle with hardened steel instead of brass you will be fine. 