The year Germany reaches ~100% renewable energy for electricity, will also be the year they install the most renewable capacity in history. It is very unlikely that the year after will see 0 renewable capacity installed. Instead, prices will start to fall steadily, dramatically accelerating the electrification of remaining sectors.

Remember that both wind and solar follow very predictably cost-reduction curves. Starting a few years before 2030, electricity consumers will start to see reduced energy bills because of this.