It doesn't sound like you're even remotely informed of what's going on in the Skype world lately. Basically, the old infrastructure was peer-to-peer, and over the last couple of months, Microsoft has been moving Skype over to a cloud version. That's why you'll notice the announcements that a lot of older clients and platforms would stop working, and brand new apps have been made for all of the current platforms... including a brand new Linux client.
If anything, this year is the biggest change Skype has EVER HAD.
No guarantees it won't still suck. (Though it's completely new, I think it's Electron-based or something.) Just saying, there IS a huge momentum at Microsoft to rework Skype from the ground up.
Not really. A supernode isn't really client/server architecture, even if it's hosted by Microsoft. Communication between users is still peer-to-peer. Supernodes are basically meant to help you find the client of who you're talking to. (Like the master server in many FPS games, it's just helping you find other players, one of the players or a dedicated server someone is running is actually hosting.) You could see this behavior recently even, in that if you sent a chat or a file, it could not go through unless both your client and their client were simultaneously online.
Now, all of your actual communications are being stored in Microsoft's cloud infrastructure. This means the actual content is centralized, and can be delivered when the other client is not present, which will help a lot with mobile. It also means it's more able to be reached by government data requests, of course.
If anything, this year is the biggest change Skype has EVER HAD.