I would have to disagree with them becoming obsolete adamantly given the robust research on leucine. Also, I personally think they SHOULDN'T become obsolete and that they may become more utilized. More and more BCAA products are bringing focus to a higher leucine content (leucine loaded, etc). I personally don't think isoleucine and valine are too important in general and they seem to be pushing the leucine aspect (as it actually justifies a lot of their claims on the product). Also, as IF has seemed to become more and more common, BCAAs are suggested and incorporated by a large portion of that crowd. They are also one of the only products that you can buy at idk Walmart or mostly anywhere that directly and scientifically increases MPS. I personally prefer pure leucine in most cases but I do take BCAAs for a few reasons; 1. I partake in "fasted" training 2. to inhibit catabolism during lengthy periods where I'm not feeding 3. to spike MPS when I'm not hungry or between meals (see The Solution's brilliant post in this thread). 4. during cutting they're valuable in that I can consume more calories from carbs and fat by "topping off" MPS with them for a very small caloric value. Now, total protein is an absolutely crucial factor but this way I feel I can get away with say 1-1.25 g protein/lbm vs 1.5 g/lbm which I may need without supplemental leucine to at least feel as though I'm putting myself in the most anabolic environment possible. And 5. honestly, a nice tasting BCAA slushy/drink is a heck of a lot more enjoyable than pure leucine IMO. Oh and also, most importantly by FAR, I think they are invaluable for patients and elderly folks that are suffering from muscle atrophy. I have seen atrophy treatment protocols with supplements containing HMB but pure leucine appears to be taking the spotlight given the efficacy and how much cheaper it is.