Matthews may pace to at least attempt to get close. But you're right, in that getting to 500 is one thing. 600 and 700 will be attainable. 800 may be doable. That's double the goals he has now. But beyond that, at the age he'll be trying to do it at, it gets tougher.
To put it in context -- which I always found mind-bobbling -- Matthews will need to average from here ten 50-goal seasons to beat the record (not accounting that Ovi will now blow through 900).
For someone not even in the league, or born yet as Nineteen67 pointed out above, that player will need to have 18 50-goal seasons or 15 60-goal seasons. It's crazy thinking about it like that. Even crazier that we witnessed Ovechkin do it, when we thought it would never be done.