Fallout fans were worried that Fallout 3 would be Oblivion with guns. Now TES fans are worried TESV will be Fallout with magic (or something?).
I think we won't have much to worry about. They'll take things that worked (better looking characters, better voice acting, better overall implementation of the engine) but leave out things that just wouldn't fit (VATS for one). VATS is such a Fallout
thing that I can't see it appearing in a TES game. I can't see experience points showing up.
hardcoe mode, yes, because TES mods had it before there were even any Bethesda Fallout games. Perks? I wouldn't necessarily mind them if they were done well, but I can't see them fitting TES's gameplay style and I don't expect they'll be added. I think the devs love their TES traditions as much as we do. They're making the thing, after all.