You still have to bring Cait to Evergreen, but there will be a new option to refuse her conditions and search on your own. Barney will still be found at the same spot but it won't be highlighted on the map any more. You'll need to bring Cait with you to actually advance the quest but if you didn't already happen to know where to find Barney, there will be an Investigate option on the right tile to let you know you've found it, greyed out when Cait's not present.