It is the year 2020: why should I use / learn D?

[lagfra]

https://www.reddit.com/r/cpp/comments/9vwvbz/2018_san_diego_iso_c_committee_trip_report_ranges/

By 2020 C++ is planning to introduce:

* Ranges
* Contracts
* Concepts (`__traits`)
* Proper constexpr
* Modules
* Reflections
* Green threads

Right now it already has:

* `auto` variables
* Ranged for (`foreach`)
* Lambda expressions and closures
* `nothrow` attributes
* Proper containers
* Proper RAII

In no way this is the usual trollpost (I am a participant of 
SAoC). What bugs me is the shortening distance regarding what D 
has to offer with respect to C++. While D for sure has a way 
better syntax (thinking of template declarations, `immutable`, 
UDAs) and a GC, what are the advantages of using D vs C++ if my 
goal is to build a complex system / product?

TL;DR: what will D offer with respect to C++ when almost all key 
features of D are present in C++20(+)?