From June 2019 the Windows Subsystem for Linux (WSL) will feature a real Linux kernel. While the current WSL1 is just some kind of wrapper, an incomplete Linux distribution with lots of limitations, the new WSL2 will feature full system call compatibility.
To my mind this will make use of Hyper-V, which in turn will likely block access to VT-x for other virtual environments such as VirtualBox and VMware. So, quite a clever move by Microsoft.
Luckily they’ll support further development of WSL1, too.
Read more at Microsoft.