Hey there,

as usual, I can't speak for the devs, but with regards to "minimal content" or "no updates", you might want to take a look here:
https://valheim.fandom.com/wiki/Version_History

In addition to that, there's a new update on the public test branch with an overhaul of the (cloud) save system + some cosmetics.

Just because it's not visible assets, or not the ones you want, doesn't mean it's not work to add it.

Hearth & Home came out September last year, Frost Caves in March.

One of the devs has given the estimate that major updates take about 6 - 9 months, but that's obviously dependent on how much goes right or wrong. Mistlands is the first new biome after the EA release, so they don't have experience yet on how much that will clash with live versions.

TL;DR: nobody knows, it's ready when it's ready.

Have a good day!