So weird to think there are Tottenham fans that don't think Eriksen is world class. The lad has 50 PL assists in 4 seasons, yet they think he's replaceable? Very few players have managed that in 4 seasons in Premier League history.
He's already in the top 20 of Premier League Assists (19th with 60).
Eriksen absolutely is world class. He's just slightly more replaceable than the utterly irreplaceable Kane. That's what we're really arguing about when people try to say that Eriksen is Spurs' "best" or "most important" player.
Eriksen's assist stats are helped by having possibly the best striker in the world to aim at (the guy with currently the best GPG ratio in PL history). But unless you watch every Spurs game, you probably don't see Eriksen's "off" periods. He's not always the imperious dictator of a football match that constitutes the bulk of his reputation: he can actually become rather anonymous for not insignificant stretches of time, particularly during the first few months of each season.
Overall, Kane and Eriksen have a highly synergistic relationship: one that has bolstered both of their respective individual stats. Losing Eriksen would be a huge blow and I don't think anyone is trying to claim otherwise (at least I hope not!). Without a creative-minded AM of a PL-ready standard ready to step in, losing Eriksen would make top 4 a real struggle (if, e.g., Lo Celso couldn't make an immediate impact).
On the other hand, Kane has scored up to ~40% of the team's total league goals in a couple of previous seasons, and losing him would mean dropping back down to the pre-Poch+Kane era[1] of struggling for EL. There is no vaguely realistic replacement for Kane and that's if
anyone could do his job without a dip in quality.
[1] It's an oft-forgotten fact that Kane basically saved Poch's job in the former's breakout and latter's debut season. Poch himself has said so on multiple occasions. Spurs were having a horrible time in the league and really struggling to score for the first few months. Kane's goals salvaged that season, which is why Spurs' ascent to the top tier of European football can be traced back to the arrival of both Poch and Kane. They started the "Poch era" together. That underlines Kane's significance to Spurs as much as everything he has achieved since.