You mean impossible mode now.
In my opinon monsters should have slighty buffed stats, but player would have no xp gain from traps and would gain a stat point every two levels. In addition, Scroll of Recall would have higher drop chance, but they would be unbuyable. No scrolls of enchanting, no named artifacts, no charming book, no items with status resistance, levitation or summons. Yes, even my favourite dog. The only quests existent in hardcore mode should be GK questline.