A dominant and therefore confident society will tolerate and listen to different viewpoints and may allow immigrants without feeling threatened but if decline starts then recent arrivals will be the first to be scapegoated as Trump does so cleverly. However defeated nations tend to be much more protective of their cultural integrity- Japan and China since WW2 have been very reluctant to accept immigrants more than necessary. If/when war comes and you have as the west does today a very diverse population it can be a major problem - as Muslim communities experienced post twin towers, as Asian and other immigrant communities are feeling increasingly in the west as the west struggles with its declining power. Immigrants are not to blame for seeking a better life and often contributing a lot to the economy and culture- but when/if war looms they are not inherently as aligned to the united sense of purpose that is required. You are right in that the west has always absorbed other cultures and taken from them as it has expanded- look at English language- a true mongrel of so many different sources to be sure! And new people bring new vigour and ideas to a culture- but they do also erode its cultural unity- something that the west seems to no longer have.

There is not a lot of coverage of Chinas alternate payments because much of this is routing payments in avoidance of SWIFT/US sanctions but there are occasional mentions of it and it appears to be centred/built upon Hong Kongs pivotal role in the global banking system and since Chinas resumption of sovereignty there a lot of CCP members are found working at the likes of HSBC!

There is a more available about the Chinese CBDC which is known to be operational and designed specifically to be an alternative to SWIFT, (Chinas (and BRICS more generally) strong belief that an alternative is required is no secret) but yes, the use of these new channels is not greatly publicised as the payments are in shadow markets where avoiding SWIFT sanctions is the purpose- Iran has continued to function economically by selling oil to China via shadow fleets and recieving payment via shadow banking/payments for well over a decade- and now Russia selling most of its gas and much of its oil to China and again maintaining the ability to source manufactured goods in return- Chinas manufacturing base is sufficient to provision both Iran and Russia and support their economy and derivative military capability despite US/SWIFT sanctions- without China in the picture those sanctions would have been much more effective. N.Koreas breaching of US sanctions via China has been even longer standing- the lorries moving goods over the border, after dark, for decades.

Other nations are surely noticing that now, being sanctioned from SWIFT is not economic collapse - as long as you have some commodities China wants...they can supply you with most of the manufactured goods required for a functional economy.

In fact very few economies could now function optimally without Chinese supply chains feeding into their economies.

Domination of trade payments/banking logically goes with domination in trade itself- and China now dominates global trade- so while US power is now hugely reliant upon its legacy USD/SWIFT/IMF hegemony, its a sensitive subject and why Trump threatens 100% tariffs on anyone breaking rank. China could achieve a bloodless coup where the dollar collapses and Yuan becomes the dominant currency of trade. Hopefully Bitcoin can be used for more international trade but such a change would require a radical change in the power dynamics where in the west banks hold our governments over a barrel of debt and China seems unlikely to allow/enable Bitcoin trade payments, even though such a move would overcome some of the resistance there is and will be to China controlling trade payments in a manner similar to how US does now.

There may be be a secondary role for Bitcoin in nations and individuals seeking to avoid both USD in its decline and Chinese Yuan/CBDC in its rise.