I've taken it upon myself to construct an idea of how Blizzard could bring back the tutorial bosses for an addittional bit gameplay. After you unlock all the classes AND beat expert training, you'd unlock a free mini adventure called "Rematch!" The six bosses would have the updated decks and revamped powers listed below, and there wouldn't be a heroic mode, but they could add a cool cardback as reward for clearing it; that, and/or some gold/cardpacks.
(something to note beforehand: I worded their Heropowers like Blizzard does, from the perspective of that character.)
Seeing as Hemmet is part of the League of Explorers, he'll utilize most of them. (not sir finley though, probably because he's Murloc racist.) And to slow down him killing you, you'll have to throw beasts in the way of his heropower.
So, whenever he or you play anything, that will give him another 2/1, pretty tough, but they still only have 1 Health, the real trouble would start once he equips the Poisoned Blade, it will automatically gain +1 attack, and work almost like the Atramedes fight.
I like it. I think Chen's Hero Power would be kinda weak for an adventure, though. What it were something like "(2): Return a friendly minion to your hand. It costs (2) less?" Or if it's supposed to be heroic-y, the returned minion could cost (0). Also, for Hemet's power, it doesn't really need to be a passive. You could just make it cost 0 and have the AI auto-use it at the start of every turn.