Which 90%? Because all I saw that was locked out was the "featured" playlists. So heroic (story and strike) and nightfall. You still have a year 1 strike playlist. All of the year one story lines and raids are still there. You can still play the old pvp maps in the year 1 playlists. Trials of Osiris and iron banner will likely be locked from year 1 players but those are considered "featured" playlists that adapt to the newest content. Tldr it's not 90% of content. Just the modified "heroics" and who would want to pvp as half the light level in featured pvp.