It may become more prevalent that the notion of eating consistently will change too. You cannot eat at a deficit for any period of time without getting pretty severe diminishing returns as your body adapts to its in vs out. 5:2 is a very simple model of calorie cycling, just an unsustainable on.
Protein and calories have the same calorie content per gram, so if you hit your protein macros then there is no downside to eating carbs, and actually for active people your gains and recovery will suffer dramatically from lack of carbs. Overloading on protein has the same downsides as overloading on carbs in simple calories in vs out terms.
I think it's fairly common knowledge now that fats are largely good (saturated fats help with testosterone regulation for example) even though food producers seem to be wilfully slow in catching up (low fat items being filled with sugar thus making them far more unhealthy).
I'm not sure I entirely buy into the if it fits your macros (IIFYM) way of thinking, but it's not a bad strategy for a lot of situations.