Kingsmarch Workers on Merc League Rollover

I've spent the last several weeks farming gold and rolling my workers to the point they are efficient to run on Standard - this took a large chuck of time and gold.

But I am pleased with the results.

My question is, and probably only staff can answer it, will my very low cost workers in standard be overwritten on league rollover?

I'd love to try merc's league, but I can't risk losing millions of gold and several weeks of time.

Thanks as always.