Well, whether we like it or not, it is clear that in terms of GDP, yes, as well as in political terms, because every time Trump comes out with a new idea, it causes the markets to falter.
The US economy is still number 1, when it comes to finance, service-based businesses and some high-tech sectors.
The economy of China is number 1 in terms of industrial capacity and production(and also some high-tech sectors).
India is still a very poor and underdeveloped country, but the Indian economy is growing pretty fast. AFAIK, India has higher GDP growth in comparison to China.
Yes, but the only country that has a real chance of overtaking the USA as number one in GDP is China. China is more developed than India, so it is more normal for it to grow less, but the most immediate threat to the USA comes from China, hence many of the political moves we are seeing today.