All they killed was the branding. The Chromecast with Google TV was such a far cry from an OG Chromecast that it was stupid for them to have the same name.
OG Chromecast could only cast and did not have a remote.
The CCwGT did still support casting, but also had a remote and a real UI.
The TV streamer is just the CCwGT in a fancy shell with probably a more powerful processor. I'll bet money that it still supports casting, and can only do pretty much exactly what the CCwGT could do.
Yeah, the google TV dongle has been the mainline product for like 5 years at this point. Honestly it's pretty good because it means I don't have to let my TV connect to the internet so it cant download ads.