As the lines move towards the camera, we change their z-values.
We have limits on z-axis, from -50 to 50, so we’ll put them into the limits uniform (x = min, y = max).
In the vertex shader: if a point is moveable (moveable attribute equals to 1), then we’ll calculate a distance, that the point passes (uniform speed * uniform time), add point’s current position, get its modulo with subtraction between max and min limits, and add the min limit 
That’s all 
You know, when I was writing that post, I came up with yet another thought about another approach.
This one: How to achieve this material effect [gif image]? - #18 by prisoner849