I can understand the thinking regards a new striker, but I wouldn't want someone who is coming to come in and challenge Soldado's first team place. I'm a great believer in having taken a player of the stature of Valencia's captain we need to show him the support and respect his reputation and record warrants and do everything we can to get him firing. I think loyalty or lack of it is a two way street in modern football, and the trust Soldado placed in us needs to be reciprocated.
To this end, I think i'd start using Kane as Soldado's understudy: came through the ranks, unlikely to kick up a fuss and increasingly proving to the uneducated masses (ie me) that he does have something about him. What happens if/when Soldado is injured? Well, part of blooding and putting faith in a youngster is playing him. We haven't exactly been relying on our striker to win us games for the past, what, 2 seasons? So if Kane has a couple of ineffectual performances on his way into the first 11 then that is to be a) expected and b) tolerated.
I think we really, really, really need to look within the squad for answers. Its big, talented and full of unlocked potential that new signings might result in becoming unrealised potential.