No one is talking about the interest of foreign elites, issue is on the those nations wanting to avoid having US exporting inflation to them by playing with interest rate. That alone suffice to make 30+ major trading nations with the Chinese sign currency swap deal.This is not in the interests of foreign elites. Why would they accept Chinese dominance of trade like this without freebies like being able to own real estate in Beijing or reserved slots for their fail children in Tsinghua?
This arrangement is actually pretty bad for the other countries and they will resist to the end unless they have no choice (i.e. western sanctions).
Beside, why the need to use a 3rd party currency when their biggest trade partner is China ?