If I had a 1080p monitor and reduced almost every setting, then yeah I think its doable though it would be ugly as sin and some settings (particle effects below 'Good') are hazardous as you cannot clearly see some mechanics (Aftershock on HC Nazgrim, for instance).
Ultimately though all anyone wants is something that is playable. I spend 90% of my WoW time above 100fps, that to me is overkill. In raids I typically enjoy 45fps, that is also enjoyable. I see dips down to 30fps during extreme busy periods, maybe even 25fps on the Malkorok pull (anyone know why that fight is so bad?). But that is a momentary thing and is still more than playable.
Also bare in mind that I have extreme settings. Every setting is maxed, 1440p display and I force AA higher than WoW permits in my nVidia control panel, as I detest jagged edges.
I think the quest for constant 60fps is silly, ultimately all we want is something that is playable, enjoyable. Don't we?