I really wonder where Samsung plans to take the Galaxy line next. My main hopes for the S8 are:
-No more physical home button. Integrate fingerprint scanner into the display or do a capacitive setup like those found on the 6P/HTC 10, etc.
-Dual-speakers. And not necessarily front-firing. I wouldn't want the front aesthetics or bezels to be compromised.
-Even better/faster camera. Possibly a dual-camera system, but make sure it's in both the S8 and S8 Edge.
-Refinements in design. They have a winning formula so I don't expect major changes, but they can do little things like remove the front Samsung logo (or at the very least, make it more subtle and more matching across all the color options). Would be great if they figure out waterproofing for USB-C ports, too, especially if this year's Note 6 is expected to have it.
-SOFTWARE - Continue refining TouchWiz. Take a page out of HTC's book and try to minimize duplicate apps. They started this process this year by putting most of their apps in the Galaxy app store as optional downloads. Continue this trend. Obviously build TW on top of Android N and make it fly with even better RAM management than this year, even better battery management, and even more customization with themes, etc. Android is getting so good that it's just now nitpicky little things. Once again, refinements.
-UPDATES/Carrier relations - This is perhaps the most important and most difficult hurdle for them to improve on. We all know the story. Samsung should exercise their weight and brand on carriers and try to regain control of future Android software updates, and of course, work to minimize carrier bloatware. And please continue the monthly security updates. They're doing a terrific job, in my opinion, of keeping up with Google for those security updates. Keep it up, and work on everything else, including providing an unlocked variant sold independent of carriers.
Those are my main wishes.