Eh. I think homegrown player loyalty doesn't mean King-esque devotion the way it used to (and we shouldn't forget that Ledley himself only stayed around for as long as he did because of his knees), but I think it *helps*, and that it offers any team lucky enough to have a committed homegrown player a couple of years longer with that player than it otherwise would were he to have no connection to the club at all. It doesn't mean we can keep the likes of Kane on a low contract forever with no guarantee of success, but it means that he'll likely consent to an extra season or two on a lower contract/playing at a lower level than he could attain elsewhere.
I have no illusions about Kane staying if we don't achieve his ambitions and recompense him at a level suitable for his talent and obvious potential. But I do think we have a longer timescale to pull that off than we otherwise would have had. And, in terms of the possibility of keeping Kane for the rest of his career, I think it's very low, but it isn't completely out of the question, given the new stadium that will allow us to raise his wages to a level that matches what our competitors offer and will likely allow us to buy better players to hopefully mount a more sustained challenge for trophies. If we manage to keep him around for the next couple of seasons of relative instability, playing at Wembley while the Lane's demolished, I think we have a good chance of seeing him here for the next couple of years after we move in, at the very least. Will he be here beyond that? Unless we definitely win some major trophies and are regularly in the CL by around 2019-2020, almost certainly not, and I don't think anyone would begrudge him a move at that point after what will have been five to six(!) years of first-team service. However, if we do manage that success, then all bets are off.
Of course, all this is just speculation based on his current status as a rising star and our relative stability so far this summer - who knows, he could bust both his cruciate ligaments and thus stay here for the rest of his career a la Ledley, or (alternately, and it's certainly a less grim scenario for him, although maybe not for us) have a barnstorming 15-goal Euro 2016 and then get 150 million-pound bids from Barca, Madrid and Ed Woodward that permanently turn his head and leave us scrambling to find a replacement on the eve of September 1st, 2016. We'll see.