The thing is though, who would have thought Ovechkin would continue to rack up 50 goal seasons in his 30s? Historically speaking this is not common. The greatest goal scorers of all-time all dropped in the goal scoring department in their 30s. Ovechkin didn't. That and health is the difference between Ovechkin and Matthews. And also leading the NHL in goals 9 times. Matthews won't do this. He's a little over halfway to 700. Let's see him do that before we assume he overtakes 894, or even 800. He has scored 368 goals in 8 seasons. Will he score that many over his next 8 seasons? He has averaged 46 goals per season. Will he do this when he is in his 30s? Might be hard, and that is not accounting for injuries. And even at around 700 he is still miles away. These records are astronomical. The fact that we are even discussing Ovechkin possibly breaking Gretzky's record is a testament to the longevity and health of him.
That's the thing though - at his current pace Matthews won't need to continue racking up 50 goal seasons in his 30s. Here's a couple of ways it could play out if he plays till age 37 (which is young, he easily could play till ~40+ and score even more).
Age 27 - 65 goals
28 - 60
29 - 55
30 - 50
31 - 50
32 - 45
33 - 45
34 - 40
35 - 35
36 - 35
37 - 35
If he does this....that's 883 goals. That's with him not scoring above 40 goals once past age 33. Ovechkin did that 3x in a lower scoring league, for comparison.
More conservative, 5 less goals a year:
age 27 - 60 goals
55
50
45
45
40
40
35
30
30
30
Thats puts him at 828 career goals. And that's without him surpassing 40 goals a single time past age 31. Ovechkin surpassed 40 goals 5 times past age 31 in a lower scoring league (assuming scoring levels stay up) - so that's incredibly conservative.
As poster above point out - Brett Hull scores 509 goals past age 26 season, and that includes all of the dead puck era years. Matthews only needs 432 goals to reach 800.
Obviously - Matthews will need consistency, good health and to age well. If he has major injuries, or if he falls off a cliff in play, then it's not going to happen. But my point is - he just needs to age well - he doesn't need to age at an all-time great level (like Ovechkin did). He's in a great position to hit 800+.