This is genuinely just my two cents; please don't value it more than that.
I was very active in the Mercurial community for a long time, and I'm still using it for personal stuff today. Mercurial solves issues 1, 2, 4, 5, and 6 in your list. I'm mentioning that for only one reason:
That was not enough.
My personal theory on why this happened largely centers around network effects. Git got big in Ruby at the same time GitHub came into existence, and I think that drove the adoption as much as anything. Ignoring whether people here feel that Git was better or not, the simple fact is that it did not matter: GitHub used Git, and the community used GitHub, so you used Git. The network effects in that kind of situation can be really hard to defeat. And while it's possible that solving items 3 and 7 will make the difference, I don't think that'll do the trick unless you can come up with a strong way to defeat GitHub's (and Git's) incumbent network effects.
I was very active in the Mercurial community for a long time, and I'm still using it for personal stuff today. Mercurial solves issues 1, 2, 4, 5, and 6 in your list. I'm mentioning that for only one reason:
That was not enough.
My personal theory on why this happened largely centers around network effects. Git got big in Ruby at the same time GitHub came into existence, and I think that drove the adoption as much as anything. Ignoring whether people here feel that Git was better or not, the simple fact is that it did not matter: GitHub used Git, and the community used GitHub, so you used Git. The network effects in that kind of situation can be really hard to defeat. And while it's possible that solving items 3 and 7 will make the difference, I don't think that'll do the trick unless you can come up with a strong way to defeat GitHub's (and Git's) incumbent network effects.