Personally, I Do not want a voiced Protagonist in the next ES game. It worked ok, for Fallout 4, but only because there aren't 10 different races with different voices(20 voice actors needed for each gender of each race). More than that, however, It took away from the immersion and only allowed for 4 dialogue choices. Imo, something like that would all but ruin TES for me. Such a big part is deciding how your character interacts with the world and different characters. The reason I like Skyrim's speech system so much is because you could persuade, intimidate, or bribe your way out(or into) a situation, as well as having one or two other things to say, besides. It helped flesh out characters a lot more. One of the reasons I don't like Fallout 4 as much is because all the characters seem like basic info dispensers. Besides a few, like Nick Valentine, they all seem boring to me. This is because you're not allowed to talk to them the way you want to, you can't be evil and you can't be a sly eloquent thief. You have to be a basic 'good guy'.
Enough about that though.
I don't think that multiple endings would work with TES either. With Daggerfall, they had to make up the concept of a 'dragon break' to explain that 6 different courses of action occurred simultaneously. To use that again would seem like a cop-out to me.