Why after the next election? You'd think that if there's anything to spur some conciliation it would be to avoid the depressing eventuality of another grand coalition, that is essentially propping up the Right on a decline. At the last election the SPD received their worst result following a grand coalition, coupled with the Greens and the Left gaining their best results, so grand coalitions aren't exactly risk-averse regards to loss of support, either.
Wouldn't it be better for SPD to keep calling snap elections untl the voters vote a certain way, rather than prop up dying CDU?