Marxism is not a science of the future. AND upon recognition of this frightening fact some marxists have behaved as though it were imperative to behave as though they have a science of the future.
"To be radical", says Marx, "is to grasp things by the root. But for man the root is man himself."
The revolution may or may not be immanent to an age. In age where one judges the revolution to be immanent it is reasonsable to proceed in deed and word as though the revolution were immanent WITH the knoweldege that chance and happenstance befall all.
In decidely non-revolutionary times, such as now here in North America, it is fair to keep the revolution in faith, knowing only that we are the root.
The rest is commentary and manouvering in the contex of the age to which one belongs (or lies imprisoned in).
Travis