I think people will expect a big rise when PoSA is released but of coarse it wont happen unless whales want to play with the market, if PoSA is already in beta testing its pretty 90%+ certain it will be released and working. I doubt there is anyone out there who is super paranoid about PoSA not working and holding out till it is released to buy. This is the exact reason why, block halfings and new feature releases almost always end in a dump, because ppl assume when x happens everyone will buy it, but it turns out everyone else knows what you know and also bought with the assumption that x happening will cause a price rise, by the time x happens everyone has already bought at an inflated price and are holding waiting for a rise and it never comes so the smart people who are still in profit dump and noobies get fuked over.
To summarize what you just said in a few words is: POSA is already priced in the markets.
That might be correct but since there are so many shitcoins/scamcoins popping out claiming to have anon features and what not, people have learned not buy anything until they see the real thing. Market is currently sideways for days, everyone might think PoSA works but how it works and if its different or just using a coinjoin tech is what they are waiting for. People don't believe it until they see it, only the cloak community believe that PoSA is working but outside of it no one believes it yet until they see it working and fully functional with their own eyes.
Its pretty much a waiting game now.