I wish I knew what people would trust more - I'd be loading up the trunk with that single thing right now.
Ultimately I believe people will always trust real, tangible, assets that have their own value independent of which currency they transact. Be it real estate, commodities, a powerful brand, etc.
Military superiority gave USD the reserve status that it enjoys today backed by a booming economy and fed by strong technological advancements. Had it lost the II WW we might be discussing the fall of the Deutsche Mark now.
Let's be clear, after 1945 the entire world acknowledged US' as the leading economy, like unquestionably. In part because it came out relatively intact out of the war, whereas UK, Germany, France, Japan, Russia had suffered more damage. (Yes yes, USSR and Japan later came as contenders but they were never real competition across all quadrants).
So naturally USD became the worlds reserve currency. First backed by gold and lent to its allies and later converted to fiat. Everyone was transacting with dollars anyways and their debts ought to be paid in USD as well (btw much like China is doing today with emerging markets like Pakistan, Africa etc.)
Today I don't think military is the key protecting the dollar reserve status. Call it the law of diminishing returns where nuclear access leveled the plain field. I do think decades of seeing USD as a safe store-hold of wealth, a trustable mean of transaction, play a bigger role in institutions and individuals choices. Just like Microsoft owns that little space in your brain that pushes you to accept their newest pricier offer rather than switch to a different provider even if it the latter is marginally better. So do people tend to buy a weaker, monetizable dollar - that's what I meant with inertia and 'boiling frog' reaction speeds.
That holds until it doesn't. If a new provider comes up with a better proposal than Microsoft or if it tries to increase the prices too fast, there's only so much 'laziness' that would prevent institutions from re-arranging their systems and processes and ultimately move to the other offer.
Question is: is USD pushing the boundaries of 'inertia' too hard too fast? My guess is Yes. Is there a better provider somewhere? My bet is Yes (China).
Will the DCEP be the final nail in the coffin that reduces the adaptation hurdle so much that it will make it super easy for institutions to switch away from a debasing dollar? - who knows.
I like those odds but I don't like how that future looks like. I'd rather have US ruling the world than accept a new non-western leader for which my values and culture are more distant from. But this isn't about what i'd like, it's about how do I protect myself and the ones I care about from a harsh, and in my view inevitable, reality.