It would be absolutely nothing like your analogy.... While Kane is a fantastic number 9, he is also a very good number 10, I would say that Lloris isn't even amongst the best 25 players in the Spurs squad who could play left back, whereas Kane is probably in the best 3 or 4 at playing number 10. Kane moving to number 10 is nothing new for us, I noticed that it happened a few times for us last season with Son/NJie playing further forward than him when we were chasing a game.
Also if you watch Kane, he has a preference to pull out to the left and come back inside on his stronger right foot..... From the videos I have seen of Janssen it appears that he likes to do the same but instead seems to instead naturally pull out to the right. If chasing a game we could use that to exploit Alli making his runs through the centre with Eriksen and Lamela, our attacking right and left midfield players playing their usual game coming inside.