Recent reports suggest that many countries are actively considering holding Bitcoin as a reserve asset. If more nations pass legislation to officially own BTC reserves similar to El Salvador, we could see a significant surge in demand driven by government accumulation.
Just imagine if a majority of countries adopt this approach. The impact on Bitcoin’s demand and value could be enormous.
We can understand that many countries are considering to have Bitcoin reserve because they want to follow US and China. They know US and China hold many Bitcoin for a big reason, US and China won't waste their money and time if Bitcoin has uncertain future. Well, I'm not sure El Salvador triggers them to have Bitcoin, it is mostly caused by a big country such as US and China.
The demand of Bitcoin will be always increasing even without the issue like US Bitcoin reserve. Since Bitcoin price is getting higher in a short time, more people will try to join Bitcoin investment. However, we must admit that there is significant impact when Trump decided to have Bitcoin reserve for US.
Regarding the price, it won't easily increase significantly in a short time. It should take time to increase massively. Having many countries with Bitcoin reserve won't increase the price instantly to $1 million. CMIIW 
From idea to proposal and actual enforcement, there are many challenges and surely the journey is not easy and smooth with many possible failures along the journey. You can see that in the USA, there are some states that try to push state Bitcoin reserves but many states fail at very early phases.
Every good thing must have some obstacles. Moreover for the new investment choice like Bitcoin. It is not surprising if there are still many bad statements on it. However, those who stated fail, they may not know well Bitcoin investment. Or they are the people who have no patient and can't hold for few years. Another reason is, they may be Trump's political opponent. So, they are trying to bring down Trump's reputation with negative statements in the media.