I am surprised they did not announce LAX or SFO. Seems like an obvious gap on their route map to me. And, I think YX can generally hold its own against WN due to the different market niches.
SFO makes perfect sense, but it's a rather weak market in the winter. In the press release Hoeksema said they were currently evaluating other expansion possibilities and expects to make other service announcements in the "near future". I would hardly be surprised if SFO was part of that.
The people who do the market analysis, the route planning and the scheduling don't have anything to do with the process of trying to avoid the F/A strike. They need to move on as if no job action was possible.
Now of course the company *does* indeed face a possible job action, and undoubtedly people on both sides have done contingency planning in case things are not resolved in time. Short of a long, disasterous strike or CHAOS session (which is certainly not impossible) planning should and will go on as normal.