Just wanted to add my voice to those who dont like auto-replenishing potions. It just sounds incredibly gamey and artificial.
Maybe potions could have several uses or 'charges' before they are depleted. Say you start with a small bottle which you can drink from 5 times before having to brew some more potion. Then, later on, you can replace your small bottle(s) with bigger bottles that can hold more 'charges'. I think this system could encourage players to use their potions more often.
I do like the idea, but you know what, it's probably still not going to make the people who didn't use the potions before, use them & I don't even think this new auto-refill system will either.
I said it before & I'll say it again... If people get a few hours into TW3 & they haven't used potions for awhile but they're doing perfectly fine, new system or old do you really think they're going to actively make an effort to even bother drinking the potions & activating mutagens?
I really don't think so. Unless some crazy boss fight comes along that they get stomped on & they go "Oh yea potions" (Or most likely they just ask online), they're going to completely ignore the feature anyway.
I'm speculating bullshit of course, but it's honestly what I personally believe. There's no point ripping the old system out & taking away an integral part of the Alchemy/Witcher experience that the core fans love, in some attempt to get new people using their potions which I honestly think won't work anyway. That's my belief & it's going to be frustrating to see it if it happens.