There isn't any new catchup mechanism in 5.2, and justice points are going to be completely useless.
So the best item that fresh 90 could get is (other than LFR which is once a week and valor with really small cap) new malevolent gear which is 476, far superior compared to heroic items or justice items, and has unlimited caps per week.
So basically PVP has become best catch up way for casuals, so expect to see tons of bots in next patch.
It's back to TBC where people grinded PVP gear to PVE