I have 4000 hours into Valheim, and still enjoying it immensely. My son quit playing after Yagluth, but I kept at it. I explored a lot of our map, but was very cautious to check when Mistlands biome appeared on my map and gave those areas of the map a wide berth, easy peazy.

I also started a new character and a new map and am loving the solo play a lot. I am at the point in this game where I am nearly indestructible, so I downloaded a mod that allows me to decrease my armour and increase enemy strength, albeit it still takes 2 deathsquitos coming out of nowhere to kill me while taking on an entire Fuling garrison.

There are a lot of ways to continue to enjoy Valheim, without interfering with your game when it is updated to include Mistlands, but I get the feeling you know that already.