As far I know the option for airlines to nominate someone to TSA PRE will go away soon. You can gain PRE either via applying to PRE itself ($80 fee afik and if ok'ed it is valid for 5 years) or via Global Entry ($100 fee and also 5 years).

I will have my Global Entry interview soon as legal resident here. I signed up for GE because of no interviewing location for TSA PRE in the SF Bay Area (only out in Stockton), while GE interview is at SFO.