The demand for potions might go down but people will still want them. The potion sickness thing really only affects boss fights. People still use potions at other times. Also, flasks and elixirs are still going to be needed so it's not like alchemy is suddenly a worthless profession.
As for herbs, inscription will almost definitely increase the demand, especially when the patch first hits and 65492387458345 people all try to powerlevel it at once. That shouldn't affect alchemist profits that much though. Yes, herb prices will increase, but then so will pot/elixir/flask prices.
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75 Rabbit/75 Sheep/75 Coeurl/75 Eft/75 Raptor/75 Hippogryph/75 Puk
75 Scorpion/75 Wamoura/75 Pixie/75 Peiste/64 Sabotender
51 Bird/41 Mandragora/40 Bee/37 Crawler/37 Bat
Items no one cares about: O
Missions no one cares about: O
Crafts no one cares about: O