Well... I can't blame you for that. After all, Apple has just released its newest machine in an 8 years old case.
Why don't just fix the fan issue and recycle the cMP, as well? Please, Apple!
[doublepost=1523376291][/doublepost]Anyway, IMHO, I think there are a few more reasons why Apple hasn't come out with a mMP in 2018:
* no new chips to set the mark on speed (even a change to AMD Epyc wouldn't give much boost to all Pro users, only to a niche), neither CPU nor GPUs, and beat the iMP in the low/mid performance BTO options. We may need to wait for some new Xeons or Epycs with higher ST specs.
* the need to design a T3 chip and a new architecture where some bottleneck processes can be dealt with and the CPU can be relieved of the burden
Finally, I think there are still chances that the mMP will position itself at the price range of the tMP, offering BTO options beating by far the iMP 18 cores with Vega 64. However, some base configs will cover the void of a non-crippled machine between the (new?) Mac mini and high-end mMP. 3.500/3.999 for the base machine, with performance close to the iMP base/mid config could attract all Pro users, not only super-pro videomakers and HPC scientists