Ok so this is not verified but I definitely believe there is strong evidence to indicate that it is going to be a spider clone behind the new scarlet spider costume...just not the one we were thinking of...
Look at the below image which is from a preview of Amazing Spiderman: Spider Island Issue 6:
As you can see from the recap and the image here...it clearly shows that Kaine has been cured of his mutation and even looks like his degeneration has been cleared up too...
Also Kaine always viewed his clone brother Ben in high regard (even though he tried to kill him many times) and I believe he would take up the mantle of 'The Scarlet Spider' in his memory...
Now I havent been reading Spider Island and in the image it clearly states Peter cures his clone brother...so this could mean his powers are stripped as well...so I may not be right...still I think it would be really cool if Kaine is the new scarlet spider...
What do you guys think?