Also, a climbing mechanic would be kickass if they ever added enemies like this:
http://www.wired.com/news/images/full/colossus03_f.jpg
Next, seafaring. I dunno about any of you, but I'm sick of caves. There are other possible locations for dungeons! Like, say, islands, reefs, underwater ruins (and finally put the waterbreathing enchantments to use), etc. Plus it adds new possibilities for enemies so we can see some of TES' marine lore in action. Also pirates.
After that, I would say flight, by use of airship. After you get to the high levels and have discovered most everything in the world I think giving the player an airship would be a cool addition if it's only made available late in the game.
These sound like flights of fancy, yes, but TES6 is way, way down the line and by the time it's in development hopefully it will be on the Xbox 720 or PS4 with modern processing power (of course they wouldn;t develop it on a PC, let's not get TOO excited here)
Anyway post your wishes for innovations to make