China is surely on the rise, but India's future is far from certain. Even by 2019, IMF forecasts place India with a considerably smaller economy than the UK!
I strongly disagree that the major EU nations will be irrelevant in world affairs within the next 10-15 years. For example, by 2019 the UK will be approaching a $4 trillion economy according to the IMF. That is only 5 years away. So imagine how large it will be 15 years away from now? Maybe $6 trillion? Also, the UK is forecast to eventually overtake Germany as Europe's largest economy in the next 15-20 years due to higher population growth and higher GDP growth. That doesn't look like an irrelevant country to me.
Canada and Australia are far smaller and weaker than the major EU countries, yet they do just fine without being in a Union like the EU. In fact, Australia and Canada are very active and influential on the world stage, and China considers Australia to be a major player and partner in the East Asia/Oceania region, both in terms of diplomatic matters, military balance and economics.
Britain, Germany and France are much larger, more powerful and more influential than Australia - so if Australia can hold its own in talks and agreements with China, then Britain or Germany surely can!
The rise of China is not somehow going to suddenly make European countries irrelevant. That is a silly notion.
Also, while China has already surpassed the major EU nations, the only other Asian county that might also do the same is India. No other Asian nation realistically has the potential to overshadow the major EU nations.
So 30 years from now, even if India does emerge as a major power, the Europeans are still going to be major powers too. GDP rankings would probably be something like:
US/China/EU
India
Japan
UK/Germany
France/Brazil
Russia
Rest of world
Russia will continue to lag behind the above nations if it continues to pursue its destructive foreign policy and over reliance on exporting fossil fuels.