The same could be said for anyone hosting files. There is no saying how long that the OGR forum will continue support our post (Hopefully a long time). The nice thing about thingiveser is that they are own by stratasys one of the oldest 3D printer manufacturers. The aren’t likely to disappear overnight.
As for legal action any platform could face similar issues. However, the likely hood of that becoming a problem is low. It would take work to find everyone that download your file and then tell them that the file is no longer under creative commons license and that they need to start paying for it. I’m also not sure they would have the legal authority to do that since the user that uploaded the file also agreed to a creative commons license.
My point is thingiveser is a great platform for sharing files.