Unfortunately, I don't see the rest of the series' seasons being released.
I mean, to my knowledge, the last release of the Netflix shows was Iron Fist season one as a region free - Defenders and everything after it hasn't been released at all. And with the conflict between Disney and Netflix I'm not sure they ever will be. I have everything that's been released on blu-ray except Iron Fist (which I do plan to get), and I would definitely buy them all in a heartbeat, but I'm not holding my breath.