Retaining the current structure is a pretty big get for the owners. Remember salaries are now at 2017 levels. The bonus pool for pre-arbitration players does avoid the need for earlier arbitration. And frankly the player's proposal of free agency of 6 years OR 5 years/age 29.5 would affect maybe 10-20 players a year and the best get locked up early anyway, so it is really not a big ask.
Then the expanded playoffs and no salary floor are other gets for the owners.
Agree on the 42-man roster. I might even make it larger (your taxi squad idea). As long as the 3 years of options remain the same it is hard to see how much it would abuse players. The NFL saw that this year with relaxed injured reserve and larger practice squads. Larger rosters are needed and more players making the minimum (like $150K for 40-man players) is not going to change much as long as it counts towards the CBT limit.
The players need more wins than the owners here because the owners dramatically won the last round.