Maybe.
But then right now this team is very capable of winning the premier league. I believe if they were still playing at white hart lane this season, they'd go on and win it for me.
I doubt any of them would want to leave personally. Why would they? The quality at Spurs is as good as any other team in this league, challenging each year, playing in the biggest competitions and playing well there too.
The only way I can see Kane and Alli leaving Spurs, is by the way of an audacious bid that matches that of Mbappe/Neymar which Spurs couldn't turn down.