UK: No. In decline.
USA: Yes. Arguably in decline, but still has a very powerful military and probably will for some time. Natural resoruces still abundant.
Brasil: No. They will continue to be the biggest fish in a little pond. Nothing more.
Canada:
No. As per the US, but weaker in every capacity.
Australia: No. Largely irrelevant on the world scene.
Japan: Maybe. In decline due to population, and has very little natural resources. Powerful economy right now, but it is on its way down.
China: Obviously. They are drowning in money and still have huge growth despite this crappy economy.
Malaysia: Why is this even on the list?
France:
No. The only things the French are good at is drinking wine and spreading STDs.
Italy: No. Their political environment is WAY too unstable. Average chief executive lasts less than a year. Their most effective leader in the past century was probably Mussolini. Sad, right?
Russia: Possibly. They have the natural resources, but the heavy mob presence, climate and internal disorganization is a problem.
Germany: No. Solid economy, but not really expanding. Like Brazil, they are the biggest fish in a little pond.
Sweden: No. Why are they on the list? They haven't done anything of importance for over 200 years!
India: Maybe. Has the potential to unseat China as a major manufacturing hub, but has done a very poor job realizing such potential.
South Korea: No. Essentially a US puppet state. As soon as the US stops supporting them, they got nothing.
Iran: No. Sanctions don't appear to be going anywhere.
Spain: No. Virtually a state-run economy at this point, and those never seem to do particularly well.
Another Country in Europe:No. UK and Germany are the most important nations there. The rest are either dead weight or too small.
Another Country in Asia: No. See above.
Mexico: No. Similar to Russia, underdeveloped and organised crime too powerful. Mexico is half a step away from being a full narcokleptocracy.
WWIII: Eh, maybe. If it does happen, it will be a stomping of someone. Only a few nations in the world have relevant militaries, and most of them are currently on workable terms with one another. Yes, there are misgivings and grudges, but nothing in the foreseeable future would make them particularly influential. It would require some sort of major catalyst for that to happen. Inevitably, something will happen at some point to thin the herd, but I don't foresee what it could be at this point.