"Did Karl Marx project an objective outer limit for capitalism ? I thought it was a subjective outer limit, the consciousness of the working class."
Marx believed and wrote that capitalism, like all other class societies, had an objective outer limit, which would result either in the reconstitution of society anew (in the event that the masses are able to carry out their historic mission), or in the common ruin of the contending classes (if they fail), as the Communist Manifesto stated.
Capitalism's chief distinguishing historical characteristic is its constantly revolutionizing instability (the Volume One discussion); its theoretical outer limit imposed by the tendency of the rate of profit to decline (the Volume Three discussion). In the past, the road to that outer limit has been disrupted periodically by the wholesale destruction of capital, which has been followed each time by a new period of accumulation and growth. One cannot exclude that possibility for the future, of course, but no Marxist ought to slight the prospect of "the final conflict."
A revolution occurs when neither the ruling class nor the exploited class(es) can continue to live in the old way, a mainly objective condition. As that condition approaches, the subjective factors take on far greater importance in determining the subsequent course of history, but they are intertwined with, not independent of, the objective conditions.
Ken Lawrence