The workers are in the harvest?

In a new comment on a post from about this time last year (“What we need: more workers“), friend Gary Jennings writes:

Thanks for the solid article. Just a reminder to all believers that the workers are in the harvest. Multiplication will occur when we equip every believer, especially new believers, to be disciple making multipliers and intercessors. We have the tools. It’s going to take intentional leadership.

This is technically very true, and I reiterate this very point a lot.
However, it struck me that we ought to give a caveat. We (I) am sometimes tempted to think of this idea of the-workers-are-in-the-harvest as a “silver bullet” solution for the remaining task: that the first movements started will generate all (or at least most) of the workers needed.
The reality I’ve found is a little more cynical. Most of the time, movements seem to generate enough workers for their own harvest, and a little more besides for nearby harvests – there is a “local flooding” effect.
But the waiting harvest is so big and so vast – thousands of millions, ‘at least’ over 20,000 movements needed, maybe double or triple that with attrition, fizzles, and movements that never get very big – that we need vastly more workers than are generated.
Additionally, the “kind” of workers necessary to cross-culturally start a movement – to operate at the E-3 level, as it were – are categorically different from the kind needed to work in a same-culture or near-culture movement (E-1 to E-2 level), and seem to be several orders of magnitude rarer.
I think this means we have to continue to be intentional about finding and raising up cross-cultural apostolic E-3 workers and sending them out.
Still, I do believe in the end we will find many of these within places, peoples and movements outside the West. So in a sense much of the workers are in the harvest – but they will not easily emerge.