We should be able to get Kane, but maybe not this summer - infact, definitely not this summer because Tottenham will be riding the crest of a wave, and giving it large because the were in the oh so close 'title race', only to be denied by Leicester. The perfect time to target him would be 2017 or 2018 - by then the Tottenham bubble would have burst in all likelihood (Pochettino has been repeatedly linked with Real Madrid - once he goes, they're unlikely to recruit a manager of similar class, especially when the top teams are strengthened), and hopefully - Mourinho would have re-established United as a top club. The new broadcasting deal will make it harder for us to extract marquee English players from top-ish clubs, but if the projected on field success (hypothetical, of course) makes us an enticing destination once more (particularly for British players) - we could then roll out the carpets for the likes of Kane with some gumption.
As things stand, we have to sort out a lot of things in the coming transfer window (and that takes priority rather than chasing Kane), and engaging in protracted negotiations/ mud slinging tactics with Levy would be unwise because he'll either tell us to **** off, or string us along for the whole summer in a manner not too dissimilar to the way wasted Madrid's time last time around for De Gea. Sort the midfield and defense, get some pieces for the attack, and then add some cherries on top - in the form of Kane or Dybala or Griezmann (also unlikely to move this summer) or *insert muppet target - what have you. Right now, transfers of that magnitude might be a season too soon, and I have no confidence in our ability to pull 'em off to be honest. And it'll probably take a near world record deal to sign Kane too - given that Sterling was signed for £49 million, and Kane is a more proven player on a semi-lucrative long term contract.
That said, maybe Mourinho can launch the pre-emptive charm offensive starting this summer, and legally tap him up - like he did with certain players in the past (or like Madrid did with Bale), with one eye on his second season at United - when he would (presumably) launch the bid. Or, this is all guff created the media to generate clicks - can't discount that possibility either.