HerInteractive doesn't seem to be continuing their "Nancy Drew Dossier" (their casual) series. The first Nancy Drew Dossier game came out in 2008 and the 2nd one in 2009, but there haven't been any since then. They ported Shadow Ranch to iPod and iPad in 2011 as the first in a new "Nancy Drew Mobile" series, but don't seem to be continuing with that either. I think they were just testing the waters. Their PC games seem to be what's doing best for them.
City Interactive seems to have given up on both PC adventures and casuals for PC. Their ***website***
only shows casual games for Nintendo DS, not PC. And no adventure games at all.
Only Frogwares seems to be successful at both PC adventures and casuals.