I am not surprised about Lowe leaving Mercedes. There has been plenty signs that he and Toto are not quite aligned on a number of things. You could also attribute most of Mercedes' poor reliability in 2016 and possibly the last three years to Lowe; as Director of the technical side of the Mercedes team this was his responsibilities. Hamilton's technical issues which included two engine failures, happened on his watch. Looking inwards from the outside, one would guess that he has underperformed really. Hence, l am not surprised that Mercedes are talking to Alison as a replacement for him. It is also interesting that Mclaren were quick to state that they were not interested in Lowe. That said, Lowe would be great for Williams as he brings tons of experience from working with Mercedes with him.
I would be surprised that Williams would risk their 2017 campaign by releasing Bottas. It is interesting that Di Resta is not getting any mention at all in all this. Mercedes may have to go with their rookie Wehrlein and hope for the best. I am not sure why Mercedes lack confidence in Wehrlein, especially seeing how well Verstapenn and Sainz are doing. They probably do not rate their rookie as highly as Verstapenn and Sainz.