Been over this repeatedly with various posters, but I disagree. The "buy a backup striker ready to come right in and be awesome if the first choice gets injured" isn't the right route for us to down imo. It's likely to be very expensive and that player is likely be get unhappy when/if Kane is fit for extended periods of time. It's the failed approach of Emirates Marketing Project, Chelsea etc.
I would rather see us develop a talented player with whatever game time is allowed by Kane. Of course I'm not saying bring in a 17 year old that won't be ready for first team football for 2 years, but someone like Embolo, Dembele at Fulham or perhaps Batshuayi (though on the expensive side) seems like a good idea to me. Our focus shouldn't be on getting someone that can hit the ground running.