Yes, normally the addition of further hak packs is frowned upon given the download and other such issues. However, while Layonara is of course quite a gorgeous world, there are quite a few haks out there that are probably far superior (in my opinion) than to what is currently used in the world. I'm sure the team has considered many and over time some have thankfully been incorporated (such as the Elven interior and the Dwarven city hak).
The work it takes to blend every thing together without bugs or error must take considerable time. However, I personally would love to see more winter tilesets such as the one above - winter cities (and given the dark ages, this should be expected due to the weather change), winter forests, etc...
I'd like to see more "frozen wasteland" mountain peaks like in Michaelis's album section, though to get that scenary you'd have to incorporate and additional sky hak (nanosky hak last I remembered). I would assume given the recent post by Leanthar about Layonara and it's future where he mentioned the incorporation of new haks, I would hope these winter haks would be on the list.