In around 8 years (when he's likely eligible) he'll be in (or soon thereafter.....barring injury). He'll reasonably sit:
Top 25 all time goals
Top 50 assists
Top 30 points
There are 6 people with 1300+ points that are not in the HHOF. What are you willing to bet that any of them don't get in?
Jagr (not yet eligible)
Crosby (not yet eligible)
Ovechkin (not yet eligible)
Thornton (not yet eligible)
Malkin (not yet eligible)
Kane (not yet eligible)
In all of these guys (and Tavares) favor as well is that they put up those points in a lower scoring era. It's always probably best to judge players on their era too.
Top 5 for points in the NHL since Tavares rookie year (16 seasons including this one):
1. Crosby
2. Kane
3. Ovi
4. Stamkos
5. Tavares
Tavares goal scoring is probably even more impressive.
Top goal scorers in hockey since he came into the league:
1. Ovi
2. Stamkos
3. Tavares
4. Crosby
5. Kane
Taking things a little further, by the end of the season, Tavares is going to rank in the top 5 for goals scored over the last 20 seasons despite not playing for 4 of them (behind just Ovi,Stammer, Crosby and Malkin)
NHL "adjusted for era" totals have him currently ranked 31st for goals and 40th for points all time. If he makes it to the 600/1300 level you are predicting, i'm not sure how it translates but its going to certainly be a top 20 offensive producer in history.
Considering those numbers, his peak (2x Hart nominee), junior dominance, international success and even a bit of unique acclaim with being the first "Exceptional status" player, hes pretty much a lock for the Hall and he still has a few years to go for a cup as well. Its all a matter of when he makes it in really as we could have more than a few great players retiring around then as well.
Can Tavares hit 500 goals this season? He needs to get 26 goals in 45 games so will probably have to wait till early next season.
I think he will hit 1100 points though (needs 23 more points to that milestone)