It will definitely be playable, but you won't be able to run it in full HD resolution at ultra graphics. I'm guesstimating that you can play Battlefront in at least 1440x900. With medium to high settings you'll likely get around 30 FPS.
Running the GTA V benchmark on Windows 10 via Bootcamp yielded an average of 35 FPS with a range of 30-40 FPS. Resolution: 1920x1200 (fullscreen) Graphics settings: default (except FXAA = ON and V-Sync = OFF)
One thing to note: longer play times will cause noticeably throttling and significant FPS drops on Bootcamp. Games run with more consistent FPS on OS X, at the cost of reduced overall FPS and limited graphical setting you can change.