Whoa. You are overestimating the American military capacity by a lot.
There are regionally used strong currencies like the Euro. Us Euros mostly do our internal trade in, well, Euros, without being bombed or even sanctioned. That is quite a lot of trade.
Aside from the Euro, there isn't much of a competition in the international arena. China wants to control the renminbi tightly, which precludes its wider adoption as a reserve currency. UK is a shadow of its former imperial self, and so is the pound. The Japanese economy is too weak for the yen to be a serious competitor.
And with currencies like the rupee, you will find that few people outside India are willing to trust them. Russians now sell a lot of oil to India for rupees (and note that there does not seem to be any initiative to bomb India for engaging in this trade), but then are basically forced to use those same rupees to buy stuff from India again, and Indian exports aren't a great match for Russian economic needs.
There are regionally used strong currencies like the Euro. Us Euros mostly do our internal trade in, well, Euros, without being bombed or even sanctioned. That is quite a lot of trade.
Aside from the Euro, there isn't much of a competition in the international arena. China wants to control the renminbi tightly, which precludes its wider adoption as a reserve currency. UK is a shadow of its former imperial self, and so is the pound. The Japanese economy is too weak for the yen to be a serious competitor.
And with currencies like the rupee, you will find that few people outside India are willing to trust them. Russians now sell a lot of oil to India for rupees (and note that there does not seem to be any initiative to bomb India for engaging in this trade), but then are basically forced to use those same rupees to buy stuff from India again, and Indian exports aren't a great match for Russian economic needs.