Disclaimer: I work for Cloudinary. But: all of the services that you mention have an awful lot to offer, over roll-your-own solutions. Reliability and scalability, sure — but also, right now, just flat-out-better performance and output. From big flashy features like automatic optimization using perceptual metrics and on-the-fly responsive resizing with Client Hints ... all the way down to nitty gritty stuff that doesn’t get press releases like, say, dialed-in custom resizing algorithms... in 2017, hosted, paid services can do a lot more a lot better than anything you can set up yourself using free tools.
Images are complicated and important enough that I don't see that changing any time soon.
I'm sorry but I beg to differ. Cloud firms are trying to suffocate self-service tooling and images are, frankly, not that complicated. If you want to sell to technology illiterates then fine but this is an attempt to kill expert solutions. No FUD please
I also beg to differ. Images are pretty complicated. Just simple downscaling is obviously not that hard (unless you're like me and you worry about which colorspace you do it in, with which filter, what kind of performance for huge images, etc). But other things like lossy compression quality setting selection, automatic cropping for responsive art direction, etc etc: those things are not trivial at all.
Don't get me wrong: I'm a big fan of FOSS, and I think it's great to have in-house image management solutions based on FOSS tools like ImageMagick, mod_pagespeed and thumbor. And if your website is relatively small and the image workflows are relatively simple, that might very well be the best solution.
But I also think that for companies who just need some image management solution for their website or app, it can make a lot of sense to use an external service. It is simply a matter of dev effort and risk management. It makes more sense to have your devs focus on the core business. Building some simple in-house image management infrastructure is not that hard, but what when the next ImageTragick happens, or some new image format arrives, or browsers get new responsive image features which require more variants or server-side cleverness? Do you really want your devs to have to think about that stuff? Maybe, maybe not. If not, then moving it to an external cloud service does make sense.
Images are complicated and important enough that I don't see that changing any time soon.