SpaceX has great intentions, but it will make a critical mistake. Everyone (all 10k to one million) of the colonists he sends will need to return asap when terraforming starts. Good luck convincing future generations that, because lets face it, there will be several generations of Mars inhabitants who will refuse to return. So logistically it's not possible, and socially it's not possible. Without death. The question is how much death we're willing to sacrafice.
...Which should be zero. That's why we need to convince Elon Musk to halt colonization efforts and focus on Exploration. Once the exploration phase is done, then we head into terraforming - if we know the planet has nothing of extreme value like some thriving organism in the planet that's gone undetected.
There should be no life-long duration stays on Mars or future humans born on mars until the exploration and terraforming phase is done. Legally, morally, and ethically it's the only way to colonize Mars.