So I’m not going to try and answer that question definitively at this point since we haven’t finished up all the planning for the new potions.
What I mean is, if you make a Fishing Potion, it will still do something in the new game. It may be though that there is a better higher-tier Fishing Potion that you could have made with some of those ingredients and it would have been better to wait. It may also be that we use the current fishing potion as an ingredient in the higher-tier one and so having them on hand is really handy so you can get a jump start on making the new ones.
So I guess basically, you won’t be out anything by making the potion now and hanging onto it. At the same time, I have no idea at this point what the “min max best case scenario” is, so I’m not going to promise that’s definitely the best course of action if that ends up being something we change. All that’s set in stone right now is that a) all existing potions will still do stuff in the new game, although it may not be the best version of that thing if there is a higher tier of that potion, and b) all existing ingredients will still be used in the new game, although again the recipes may change and you will definitely need to also get new ingredients to make the highest tier stuff.
Hope that helps make it clear as mud