Never say never, especially if enough people get behind it. That said, some issues:
Healing out of battle is simple a mod of the constitution parameter, although traditionally very slow it could be very useful in dungeons w/o the ability to jump out.
The heal spell Bethany used in DA2 was similar to DAO's Creation line and it was weak, but useful. However, DAI is a bit spell burdened at times and a weak healing spell would add to the the problem, so passive or attached to another spell is better.
Spirit healing like Anders or "Blondie" in DA2 could also be added via the existing spirit tree where willpower and stamina already reside and work like proximity healing that potions can have. This could be done via a quest, but precedence is to have Solus teach - "Blondie" taught the entire spirit tree.
Potions have too many issues to list and most are just too weak to consider wasting a slot. Don't think Playing the game ever made the schedule or the effect time and scaling issues would have shown up.
The existing Proximity healing from potions seems to have issues: main character, it works most of the time, but not on team mates. This one needs validation - too many related bugs to be sure.
The whole distribution of herbs and crafting needs a revamp -they are not enemies, the drop should not change with level. For instance picking herbs should double with experience (or perk) and then have a chance of more and killing a ram should always provide leather and wool without the population falling off. The burden imposed by using only potions and so many quests - only so much rinse and repeat is tolerable - even if you choose to buy items, it would be nice to see what a store has from the map.