I must confess I struggle to see the long-term market for these services - I was working on a startup in the field for a while, and eventually decided it wasn't worth continuing.
The only thing these services really offer above desktop equivalents (which Autodesk totally dominate) is the collaboration (like Google Docs for 3D). But do you really need to collaborate to create 3D? Maybe to review/annotate etc. but to actually collaborate during the process of creating an object/scene?
To put it another way, are you going to convince your entire art team to leave behind the toolchain they have used their entire career, just so they can 'collaborate'? And if so, do you think Autodesk are going to let that happen? (Obviously not, as they bought in to the field a while ago).
[2] https://architosh.com/2014/11/autodesk-reportedly-acquires-c...