To finally get what it wanted from Renault, Nissan Motor will have to pay up.

The partners are on the cusp of redefining the foundations of their decades-old alliance, with a framework deal to equalize their cross-shareholdings headed to their respective boards in the coming days.

For Renault, the merits of this milestone are clear. The French carmaker will give up a big chunk of its Nissan stake, but will do so over time and should end up with billions of euros in proceeds. It also has convinced its Japanese counterpart to become a strategic shareholder in the electric-vehicle and software business it’s carving out and seeking to take public as soon as the second half this year.