Lenovo has announced the M720 and M920 updates to the ThinkCentre tower, small form factor (SFF), and 'Tiny' models. These business orientated machines feature affordable price tags and optional Thunderbolt 3 and dGPU.
https://www.notebookcheck.net/Lenovo-ThinkCentre-M920-and-M720-Tiny-are-the-first-one-liter-PCs-with-PCI-E-expansion.302936.0.html
This type of enclosure would be perfect for a Kaby-Lake G series SoC... dunno why Lenovo hasn't thought up with this idea yet.
Since these are aimed at businesses, my guess is that it is so they can offer a lower price point by offering options with lower powered processors, but then also be able to scale up the pricing with the addition of expansion cards.