It would be more in a sense of “choose your battles” instead of the unending spam of abilities until something dies. Very much like D&D.
Ofc the days should be shorter than RL days.
Every piece of major content in the game requires spells. Leveling, questing (dailies for gear, rep, currencies, etc), raiding, M+, PvP all require you to use your spells and abilities to complete in a reasonable manner. If you put a limit on how many spells per day can be cast, you’re just preventing people from playing the game and progressing at the pace they want. You’re setting a limit on how much content they can reasonably do in a day.
I would relish the opportunity to see how WoW players handle a survival game. I’d buy myself a 20 pack of beers, frozen pizzas, ice cream, nuts (maybe more than 20), and sweet tea and watch the Twitch hilarity.