Currently all versions bought from retail or digital store will require installing Steam. The DRM is only the Steam requirement, it checks that your key is valid, and for updates/achievements. Otherwise once installed you can play offline (but won't receive updates until you switch back).
I never really understand why people are so against DRM, i mean sure the 5 activations before needing to phone home, then sure bad thing, but steam or origin as a requirement is not a bad thing at all, i prefer that then a 'please activate product' or 'please call support and get a new activation key' man, i am sick of those things.