Well I don't think a player is ruined because for the first time in about 10 years he's been poor to average for more than a few weeks. I've also seen enough of him under Conte to know that he'll get better as the team improves.
I have doubts that he'll ever be what he once was, In fact, I recently said we've already see the very best of both Kane and Son. But to write him off completely is madness, and sounds more like that's what you actually want to happen which is very strange for a Tottenham fan.