> My question is how is this different from the late 19th and early 20th
> century development?
A small detail called "colonialism". Those teeming peasant masses of yore are now cellphone-using, TV-watching city-dwellers, living in independent states. Neoliberalism tried to keep them in check with structural adjustment and debt peonage; they fought back via delinking and forex accumulation.
> the outcome of that growing multi-polarity back then was two world wars
> resulting in the US - USSR hegemony. What makes you think that this time
> things will be different?
Because colonialism is dead. The semi-peripheries of the 1930s exploded into military colonialism: Fascism was a strategy of cheapening raw materials inputs and reinventing slave-based accumulation.
I'd argue today's semi-periphery is totally different, because its biggest economies are former colonies or neocolonies, and have grim memories of the era of neoliberal rule. As such, they want economic stability (a kind of globo-Keynesianism) and an orderly unwind of US imbalances.
-- DRR