I'm have been using P&T Assets to easily integrate with Amazon S3. Is there any option out there for cloud hosting and EE3? Can I still use Assets?
there is a brandnew add-on called treasury wich supports assets storage on S3. https://buzzingpixel.com/software/treasury
It is also compatible with Ansel (https://buzzingpixel.com/software/ansel-ee) which makes image handling working like a charme!
Assets, although in development, is not out for EE3 yet. As far as I know, CE Image and Channel Images are the only other add-ons currently available for EE3 which integrate with S3 and other cloud storage platforms.