As Rakonas mentioned, they certainly always planned on getting rid of the German name. Even if the German name didn't directly reference a king, they still would have renamed it because they wouldn't have wanted a German name. And, of course, they depopulated the area of Germans and brought in a lot of Russians, so in a way it made sense to rename the area.

But I have a question for you about your thread title. Why not name the city after Mikhail Kalinin? He was a national hero who had recently died. They named three cities after him in total, and I believe they did this with other people who got cities named after them (Russia is big). I guess they weren't too worried about redundancy. Could have been a bit confusing, but based on context I don't think people living in the Soviet Union would have actually gotten confused (ie "he said to meet up in Kaliningrad so I went to former Konigsberg, not former Tver!" probably never happened).

Königsberg means, in German, 'King's Mountain'. The Soviets renamed virtually anything that had to do with Gods or Kings. Stalingrad used to be "Tsaritsyn", Leningrad "St. Petersburg(later Petrograd)". It was probably inevitable that they would rename it. I can't say why they chose Kalinin in particular but they definitely were going to rename it sooner or later if trends continued.