Devaluing Yuan had more subtle reason: Just recently China started to sell US Treasury bonds (they have about $2 bln of them to sell)
And if you sell bonds for yuans that causes the yuan's value to raise which hurts Chinese exporters. So, devaluating it first was a way of neutralizing that effect, protecting China's economy.
Bond sale itself was a way of putting mild pressure on US in the ongoing negotiations about making Yuan part of world's reserve system.
> Just recently China started to sell US Treasury bonds (they have about $2 bln of them to sell)
China didn't just "start selling US treasury bonds". You're implying that they're offloading their bonds, they are far from it. China sold off an insignificant portion of their holdings for liquidity to bail out themselves. They were facing an economic crash and they were trying to stave it off. They needed cash to do that, hence, they sold a very specific amount of their bonds for that specific purpose.
If they sold all of their treasury bonds, it would be economic suicide because there would be so much unstableness in the global economy that every market would crash, including Chinas. They would probably fall the hardest, too.
Devaluing the Yuan has set any hopes of it being a reserve currency back by a decade at least. It was a move of weakness and has accelerated capital outflow from China as well as causing some head scratching about the competence of party leaders, because it seems unduly drastic, unless things are worse than they seem.
What you are saying is true, but won't matter anyway, because switch from USD to SDR won't be a free market decision, it would be forced upon us once US and China agree on that.
And if you sell bonds for yuans that causes the yuan's value to raise which hurts Chinese exporters. So, devaluating it first was a way of neutralizing that effect, protecting China's economy.
Bond sale itself was a way of putting mild pressure on US in the ongoing negotiations about making Yuan part of world's reserve system.