CombJelly, in my post to HailMary just now, I figured 18 months from detailed specification to product in volume production. I think the specification was written as a skunkworks last year and real resources put on right after New Years.
Now, what would those specifications include? Let me address your points -
1. HyperThreading. Dead and gone, replaced by -
2. Dual Core.
3. iAMD64.
4. Increased power budget for higher performance desktop and server parts.
I expect to see these implemented in the reverse order that I presented. A desktop Dothan may be completed faster than my schedule since the changes are minor, one doesn't need a whole lot more speed to be competitive with 32-bit AMD product (still the sweet spot through this year).