Two comments, one about nim, one about C: (1) Whether nim has a future or not depends primarily on active development AND user adoption. The second part can be very difficult, since you have to compete with other languages; and a large user size counts a lot. I know too little about nim to evaluate it, but I know a lot about ruby and a bit about python, and the popularity and usage of ruby and python can be compared. Python is evidently used by more people globally. Competing with this is hard, because who wants to use BOTH ruby AND python? People tend to prefer one over the other, settle for it, and often stick to it. They may play with new languages but if you already invested, say, +5 years into python, then switching to another language can be MUCH harder. Nim is closer to python than to ruby, if you look at the syntax and main ideas, so perhaps that should be a natural focus for nim.
The one area I feel where nim could be improved is syntax-wise, e. g. to have a look how nim could become simpler (similar to python). (2) As for C, well ... trtt said that C does not have a lot of advantages with real-world code, but ... linux kernel ... ruby ... python ... perl ... so much is written in C. I'd love if we could have an ELEGANT and FAST language that could one day completely remove C, but how realistic is that?
