The hills aren't huge, but there are five in quick succession there, and if the peloton are chasing a strong breakaway then it will be tough for the sprinters for sure. It's like 5 Box Hills in a row there.
5 over 60 km - it is a long stage, so actually they are spread out. To me it looks like a couple are bumps rather than hills and maybe the first is slightly harder than Box hill while the others are slightly easier.
I think other considerations, like road width and any potential for windiness might have more of an impact. Cav managed to win stage 13 of the Giro remember.
Orica want to retain yellow which they likely will do by keeping any breakaway in check - I doubt the lead will balloon too much.
Thinking back, the occasions when breakaway leads have got very large (outside the mountains) tend to have been when
1) something odd has happened, like the accidents a couple of years ago that saw Chavanel and Voeckler get yellow - the weather played a part then but I suspect the cote d'azur will be kind today
2) there has been a dominant sprint team that the peloton has wanted to force into doing the work, like when Cav was at HTC - today, Lotto, Cannondale, Argos-Shimano & Orica all have hope of getting a result as well as OPQS
We shall see soon enough!