It depends on what the trade price is. There are many combinations of prospects I'd consider giving up for two years of a 4-6 WAR player, with the possibility of getting first crack at re-signing him if he continues to rake, or to flip him for some other area of need if the Phils aren't contending by 2018.
The Phillies haven't had even a 5 WAR offensive player since 2011. The last time a Phillies hitter exceeded Dozier's 2016 WAR was Chase Utley in 2009. Dozier may not be able to keep it up, but he might. It seems worthwhile to gamble a little to get a player of that caliber.