Not surprised at all.
I said this was likely to happen, even if those ugly 0.1s made me a bit doubtful. But the CBS/Warner balance is horrible - this season CBS had Valor / Dynasty / Jane / Crazy Ex. Jane and Crazy Ex is ending next season, so that would leave them with nothing bar the CBS pilots (which I assume Charmed will be one of them) after next season. So it + the Netflix deal just increased its chances. It's all about profitability and Dynasty is profitable, even with crap ratings.
I guess this means they will drag it to four seasons at least.