It all depends on what Sony wants to do with the platform. If they make a PS4 Super Slim, and Digital Only Set Top Box, then it could very well happen. If they are just going to let the current PS4 models ride out the market, then I think $149.99 on sale will be the lowest we see, with either $249.99 or $199.99 MSRP after PS5 launches.
To be fair, I can see Sony making ultra slim models of the PS4 with 500tb for 99$ to save costs, though I don't see any use for that kind of digital only console but for piracy fodder.
You know it deserves the GOTY.