Won't do much... He didn't care for the Primarchs... Then again beating up Xenos did seem to be something of importance to him... I'm just wondering if the Emperor did get the Webway working would the Eldar or more precisely the Harlequins stop him or at least attempt to?
Im not sure, I would like to think it would go one of two ways A: We become friends with the eldar because they now see use as equals for using the webway B: The emperor kills them
Eldar would probably see Humanity as savages who managed to finally get something that was so simple to them working... Although if Cegorach and/or the Harlequins wanted to stop the Webway to work for people they'd know a way to fuck it up. Better to have a Webway gate fucked rather than letting Humans tainted the Webway. I imagine the Emperor would definitely kill many if not all of the Harlequins who were sent to deactivate/destroy the Webway gate. Only Cegorach knows how many Webway gates are still closed though waiting to be opened up again. The Eldar can only hope there are many more Craftworlds just cut off from the Webway waiting to come back. Just hope that the Dark Eldar don't meet them first like last time... Anyway JagdPanzer time.