The way it work in spheres of might is very elegant, since most (all? would have to check) spheres have a)ways to expend the focus, b)ways to recover the focus, c)abilities that work better if you have the focus, and d)abilities you can only use if you are focused.
The only reference to this concept I can find in SoP is a tradition drawback, mental focus, which makes it difficult to cast if you have lost your focus - that would fall between c) and d) in my categories above. So if one would want to work a system starting from that, and wanting to check all the points above, there would be need of something that requires spending focus in order to work - 3.5 made it necessary to spend psionic focus to use metamagic feats, but maybe thereīs more interesting way to apply it, maybe a boon, since in this instance the focus comes from a drawback? and something else that made it possible to recover focus as a consequence to some other action, as most SoM talents affecting recovering focus seem to trigger this way and, as I said above, is a system that I quite like. But in SoP Iīd like to see it done differently, by that I mean not through talents, since between all the options already available between handbooks and apocrifas thereīs already too many options for my tastes :P
So, again, there comes my question: has the developer team considered developing something like it? itīs evidently not in the books, so if such an idea was considered was it scrapped or reserved for later expansions? and why?