てくる -ていく (change)
Usage
-てくる indicates arriving at a present situation through a process of change
-ていく indicates moving in the direction of a future change
Examples
だんだん春らしくなってきました
Little by little, it became spring
こらから、日本で働く外国人が増えていくでしょう
The number of non-Japanese nationals working in Japan will probably increase from now on