What can be said about the conducting of 2021 JEE? In case 2020-21 becomes a zero academic year, will the JEE be cancelled as well, or will it be held with reduced syllabus? In which case students go to college without class 12? I know nothing can be said with certainty, but what is most probable?

Hello,
Till now there has been no news for the cancellation of JEE Mains 2021. Also, there is no news for declaring 2020-21 as a zero academic year by the authorities and government. Colleges are conducting their classes through online mediums.  Considering all this, JEE mains 2021 will be conducted.
But depending on the situation and if it does not recover soon,the government might take some steps to ease the process.

The conducing authorities NTA for JEE mains might consider to reduce the syllabus for JEE Mains 2021 bu that is not sure and cannot be assured until any official news is out.

The cbse has reduced the syllabus for classes 9 to 12 for the academic year 2020-21.

So please keep on your track for preparing for JEE Mains as along with your class 12. You can find various study materials in the internet.
All the best and stay motivated.

You can opt for the JEE Mains online coaching by Careers 360 which gives video lessons, previous year question papers, doubt clearing and many more for just Rs 6999. For more details please visit this link Careers 360 JEE Mains online coaching

Hope it helps