Honestly i can care less about abyss. To me the main content of the game is exploration. There should not be a cap on this, period. After you do your resin you should be encouraged to explore for loot. In addition loot from chests should scale with AR. Meaning the highest tier of chest should drop 5 star gear.

My suggestion is to randomize chest spawn but have all chests respawn each day. Since chests are randomized you can't just mindlessly farm them like you do with rocks, you have to actually look for them. However since the chests would also scale with your AR level you would get a chance at decent gear from them, especially the higher tier chests which would be fewer and harder to find if randomized. It would be a fun and rewarding game of hide and seek with chests each day, and its still optional for people who hate exploration in a adventure game for whatever weird reason. Doing this does not break the game. There is no reason for chests to not respawn in a game like this.