Yeah it's easy to forget 35 and a strike rate of 70-75 was perfectly fine until the 2010s. Average of 40 was considered world class and 50 exceptional. Tendulkar averaged 44 and SR 86, and he's the GOAT opener.
Batting averages in ODIs now tend to fall in line with test match expectations, except we're seeing test totals in 50 overs not 150. This is as true with anything 200-299 as it is with 300+ since 200 used to be just below par with 250 being the "solid score" until about 2011.
Even now in world cups, 250 is not a fun chase with the heat on and an opposition who can bowl.
Shady's numbers were meant as a joke but look a solid ballpark expectation to me. Professional era openers like Gilly, Jayasuriya, Kirsten, Waugh, Astle, Trescothick, Anwar etc would all average more now.
I mean ODI batting strategy has certainly been refined. This isn't all down to pitches and bowler rotation. Batsmen now know to a greater degree what is possible. You see this in how the glue batsmen (Kohli, Smith, Root, Taylor, Babar and the like) structure their innings to ensure their side makes 280+ on a standard pitch or to chase something down. Compare how they bat to the absolute YOLOing of the early Chappell-Hadlee games, where one batsman fed strike and the other just swung at everyone not called McGrath, Bracken, Vettori or Bond.