Perhaps the original poster meant that the "conflict" between (currently-emerging) socialism and (obstructionist) capitalism will not be necessary in the future, since socialist pre-conditions will have been met. Marx touted the same thing; I'm not disagreeing with that.

I'm going to assume (for argument sake) that this "post-scarcity" world is one were labor is unnecessary for the continued production of existing products at existing output scales (ignoring for a moment changing demographics and perhaps the "need" for R&D to solve new problems).

That still leaves land, resource and capital in the production equation. Land: because production (including food production) has to occur somewhere, resource: because the raw materials are not uniformly located in the same locales as the production or the consumption domains (and indeed most are not infinitely collectible even where they are currently located), and capital: to manage the risk and rewards on the uncertainty of the success of any venture to change the status quo (which will alter itself anyway due to resource exhaustion and geolocated "demand/need" changes).

So...what I am saying is that the "problem" of production isn't solvable, any more than entropy (resource exhaustion) can be reversed. There is always natural variability in location and resource (spatially and temporally), that are managed through the risks and rewards of capital investment; risks quantified as loss, rewards quantified as profit.