I really don't think the sky is falling on this one. According to the OP, both CA and FO lines have increased on the 757 (hardly something most people complain about). This also included a corresponding increase in Secondary lines which is also due to fact that R-day blocks can now be requested for those Secondaries. If Secondaries were increasing while regular lines numbers dropped, then I think we'd have something to worry about. PBS isn't somehow going to materialize out of this - it's just a different and hopefully better way of processing the same secondary lines we've always had.
I've always had great success bidding Secondary lines - but I agree the process is/was flawed and took some education to do it with consistently good results. This new system sounds like it will improve that process.
Drawing conclusions about it for good or bad during the inception and initial implementation is probably not a great idea, especially with the 757 and 767 bid packs in flux as well. As far as getting a Secondary during a vacation month, that's not the same animal it used to be. Sure, one can't knock out an entire month with a week of vacation or turn a 15 day R-line into 5 days. But we now have the option to use less (or zero) vacation hours in a secondary line and even work during the vacation footprint. While I'm sure the company is happy that someone might opt to do that, it might give a junior pilot some better options too. Someone who didn't even want a vacation in Feb and can't hold anything but a secondary may appreciate being able to reduce vacation hour usage and save them for a better vacation period later in the year.