I will honestly be so upset if Yahoo changes Tumblr tremendously. 
My friend made me a Tumblr account nearly 2 years ago, and I didn’t use it often. When summer came around I got very depressed, due to being isolated all the time because my “friends” don’t give 2 shits about me. That’s when I started using Tumblr everyday. It helped me a lot, and it still does. I turn to it almost as a coping skill to deal with my depression. 
It better fucking stay the same.