Let's put a little perspective on this (absurd, sci-fi) topic, and then I'll let it go.
The thesis of this thread is a self-congratulatory "The-NHL-I-watch-today-has-the-best-players-EVER!". My thesis would be that the NHL changes over time, and that the entire approach/style of the game changes; but I wouldn't argue that one era's players are better than another's. (Slightly off-topic: another point I'll always argue until I'm blue in the face, which some of you surely agree with, is that the only player vs. player comparison that makes any sense or is at all relevant is when a player is compared to his peers. Therefore, I'm not arsed whatsoever whether Stamkos has a better slapshot than Gordie Howe because it's irrelevant. The only relevant issue is that Gordie Howe dominated his era more than Stamkos his [so far]. But I'm getting off topic.)
Back to the 80s/90s issues. Let's consider a few factors before we anoint Ovechkin as the player who would score 150 goals a season in the 80s.
The top point scorer of the 1980s was Wayne Gretzky. The top point scorer of the 1990s was... Wayne Gretzky. Consider the 1997-98 season, when Gretzky was 10 years past his prime, a year from retirement, playing for a no-talent losing team that wasn't even challenging for the playoffs and was one of the lowest-scoring teams, and finished 3rd in NHL scoring with 90 points at the onset of the 'dead-puck era'. In fact, the Rangers scored only 197 goals (fewer than 26 teams this season), which means Gretzky got a point on 46% of their goals, which is about the same ratio he was having in Edmonton in the mid-80s.
Compare the top point-scorers that year (player-age at season's end in parentheses):
Jagr (26) 102/228 = 45%
Forsberg (24) 91/231 = 39%
Gretzky (37) 90/197 = 46%
Bure (27) 90/224 = 40%
So, to review: Ten years past his prime, Gretzky matched or outscored Jagr (still playing today), Forsberg, and Bure... not to mention other no-name bums like Selanne, Sundin, and Lindros. What's more, every team these guys played for had a better record (and scored more goals) than the Rangers, excepting Bure whose Canucks were just as bad as the Rangers (but scored more goals). And this was a Gretzky who was a shell of his former self, no longer going to the front of the net, winning races to loose pucks, or challenging defenders.
So, there's that. Next, consider that during his 7-year prime Gretzky outscored the 2nd-best scorer in the NHL by 71%. In one season, he won the scoring title on January 7th.
So, considering these two factors -- (1) that 10-years-past-his-prime Gretzky was matching prime Jagr, Selanne, Forsberg, and Bure in the late 90s -- just 6 years before Ovechkin was drafted -- and (2) that young Gretzky dominated his peers offensively by a margin that no player before or since can even begin to approach by half, do we really think that Ovechkin in the 80s, with a wooden stick and 80s' equipment to match everybody else and little-to-no protection from goons by the referees, would score twice as many goals as Gretzky in 1984? Let's just say I have my doubts.
In any case, these kind of sci-fi topics are nuts. I consider players' greatness and importance only relative to their peers. Ovechkin is the greatest goal-scorer of his era (well, in the regular season anyway), no doubt about it. This indeed puts him high in the upper echelon of greatest goal scorers in history. But his dominance over his peers isn't as impressive as several players in history, yet. We'll see how he does in his 30s. Looking forward to finding out!