I was having a discussion with a guild mate earlier on the effectiveness of lower level potions when the character has their stats improved to level 50. Her example was using a level 10 potion would still only restore 100 HP but her HP pool would be very large so it would have almost no effect.
My idea is to create a new tier of potions for Cyrodiil only. These potions would be locked to only be used in Cyrodiil but would be V5 equivalent potions but would not be level locked. All water sources in Cyrodiil would be converted from the current water to "Imperial Water" to craft the new set of potions.