i think they are on going subscribers to DDI with accounts and passwords still...
Right, and on the subject of browsers, MOST browsers have now demolished their NPAPI support, which pretty much means you aren't going to get Silverlight to work. I believe this is true of both Chrome and Firefox, though you can of course find older versions that will still work, if you disable updates.
Edge NEVER supported Silverlight, it doesn't do plugins, period. IE is your only real choice in 'mainline' supported browsers, and it will probably (I would assume) continue to offer support for things like Silverlight.
Note that you actually CAN get Silverlight, even the CB, to work on Linux (maybe MacOS too, not sure) if you use 'Pipelight', which required me to use an alternative RPM repo, etc. It was a slightly involved process, but mostly it 'just worked' (it also broke all the automatic updates of Wine pretty much permanently). Not sure if that is still something you can pull off or not, as my DDI lapsed a couple months back and I haven't tried to trick WotC into renewing it.