Forgetting for a second that it would be nothing like having more share-holders because shares can be bought, sold and speculated upon, relations to the means of production within the work-place matters. If there are no workers and owners, but only worker-owners, then it is not capitalism.
Papa Marx would have agreed.
On individual ownership (which is marked by a worker-owner) of the means of production.
"The means of production and subsistence, while they remain the property of the immediate producer, are not capital. They only become capital under circumstances in which they serve at the same time as means of exploitation of, and domination over, the worker." When the producer owns his "conditions of labour" and "employs that labour to enrich himself instead of the capitalist" then it is an economic system "diametrically opposed" to capitalism. Capital 1: 938, 931
Under your logic the individual worker-owner would be a capitalist; Marx demonstrates that he would not be.
Thus a mode of production with worker-owners would indeed be post-capitalism, as it has transcended class-struggle something that marks capitalims.
Indeed it is! It respects personal initiative and workerplace-democracy, but it also uses the very mechanisms that capitalism uses right now and used in the past to shift the relationship of constant capital versus variable capital in the direction of more variable, thus either stabilizing the rate of profits, or pushing it up again.
This was another thing Marx was totally wrong on.
Capitalism can sustain itself through a succesion of Busts, New Deals, and Booms. As nightmarish as it sounds.
Thus the problems of capitalism have been abolished, save for the need to work itself; this, however, would come in time and technology develops and human input becomes less and less necessary, WHILE STILL protecting the individual's right to property, liberty and democracy.