Constant trend line as a measure

There is often a need for constant x-axis line or y-axis line which is not average or median, or anything else.

Rather it is a constant which depends on the slicer applied.

This is usually the case if I calculated weighted averages, and want to divide my scatter chart ot 4 quadrants. Average trend lines deviate from my weighted average and that is a problem.

So, Idea is to be possible to put a measure in constant x-axis/y-axis trend line. So either typing the value or putting measure in, would be a nice option.

What do you think?