I've learned more about why this is a business opportunity for JRiver:
SmugMug is the leading photo publishing site (and they now own Flickr too). BUT their built-in Organize is simplistic, MC runs circles around it. Also, they have a simplistic PC-to-site uploader. Because a separate image management app (like MC) is highly desirable, even necessary, they also have a page of third-party sync/upload tools (standalone utilities, and major apps that do it).
https://help.smugmug.com/third-party-uploaders-downloaders-migration-tools-and-utilities-r11dlxDJNBzThe one they repeatedly recommend is Adobe Lightroom Classic CC. It does two-way sync, but it is a beast to use, and it is expensive, $120/year. They recommend it because there's a Lightroom plug-in that syncs local image files with online SmugMug files, including updating Keywords. That makes it very very important. But it costs twice what SmugMug costs ($4 to $6/month for most users), just to sync changes?
Yet in many ways MC is far superior to Lightroom for photo organizing, viewing, tagging, etc, etc etc. Lightroom is typical bloated, slow Adobe software. It has some good image editing capabilities for those who need them, but I get the same or better results with other faster tools. Therefore, for me Lightroom boils down to an expensive Sync tool. If MC had that "simple" ability, it could be on their list, doing much more than sync, costing much less, win-win-win.
SmugMug has API and provides a bunch of code snippets and modules for those who want to integrate. Seems like a JR opportunity to get SmugMug (and Flickr) to SELL Media Center to the photo enthusiast world.
PS: Lightroom fans might know there is also Lightroom 6 which also syncs with SmugMug, priced at $149 for perpetual license. But last year Adobe declared it orphaned, no more updates. They want everyone to subscribe to their cloud versions, Lightroom Classic CC (or simpler Lightroom CC) for a substantial monthly fee.