Autosport article by Dieter Renken (paywall)
http://plus.autosport.com/premium/featu ... 1439400959
Some interesting quotes. First about Hulkenberg
"When [Nico] was with [Ferrari-engined] Sauber we had access to all his data, and somehow we were never totally convinced," one Ferrari insider told this writer. "Ask yourself why we didn't sign his when we had the chance before bringing Kimi back."
(Personally I think this is somehow a bit weird. He outscored Guttierez 51 points to 6 that year. There is more than pace alone, which their current driver Raikkonen is living proof off)
although rumours in Germany increasingly link him to a full-time Porsche WEC drive. With Hulkenberg said to be disillusioned with his future F1 prospects
Then the plot thickens. Ferrari is apperently interested in Verstappen (although I think it's far fetched..)
However, as the Hungarian Rhapsody progressed, it became speculated upon that the keys to next year's Formula 1 line-up were not held by its oldest driver, but by its youngest.
It goes on about how Verstappen is locked in at Redbull, but possibly can get out for 2017. So if Ferrari would want to hire him, then they need a driver for one year (2016) and Bottas probably wouldn't want that. Raikkonen on the other hand..