According to a member from Bimmerforums, BMW has gone into a settlement in regards to the rear subframe reinforcement.
It's said that this firm: Girard Gibbs LLP - Investigation of BMW
may have settled with BMW. For mroe info you're said to call and ask for Melissa.
Although, each case regarding subframe reinforcement is to be treated individually.
It's also speculated that they would only repair/replace or pay for subframe reinforcements in cases where the tear or damage is seen. If your e36 rear subframe is in good condition, then that means they wont reinforce it. Also noted this doesnt mean that they will repair it. Each case is supposed ot be determined by your local dealership and their regional advisor.
Also, isn't it somethign like all e36's from 95+ had the reinforcement plate already installed?