The myth and magic Update if done together with starting scenarios are work enough for at least 5 years. I doubt Toady will get to a playable state in less than 2 years. I hope he fix the most glaring issues first (morale and stress IMO) before committing for the next long haul.
It's not being done together with starting scenarios. That's the next arc. He did say he might try to split magic into a couple of releases though. We'll see once the plans are fixed in a few months I guess. In the meantime, enjoy they bugfixes & extra stuff.
I really dislike your patronizing tone. I am at least as well informed as you (probably more) about the past & future routine of releases.
The artifact release alone took more than one year. Before that , the world activation release (0.40.01) took a bit more than two years, and the amount of features in it was far lesser than what is expected for the magic&myth alone. Remember that the myth&magic release isn't supposed to only alter the world gen and history, but everything in gameplay as well. There are features that can't be released piecemeal, or Toady would have release 0.43.01 earlier.
Besides that, Toady usually is wrong about release prospects, as he constantly says so.
I am eager for the next development cycle as well, but Toady should spend some time to fix some serious issues that are hampering the game right now. edit: I know he is going to fix bugs old & new soon. He always does that. However, he tends to leave some important one behind every cycle.