How do I tell my 4 year old he might not be going back to school?

One of the hardest things I've struggled with during this pandemic is watching my 4 year old go through all the changes that have come with it. 

My heart seriously breaks when I think about telling my 4 year old that he might not be going back to school this year. He wants to go back so bad, but at the end of the day we have to protect him and our family. I worry about how it would affect his health if he caught it and the rest of our family. His baby sister will be born shortly after he starts. There's so much unknown about this virus I just don't feel like he'll be safe going back.  

He's signed up for the upcoming preschool year (he has to do preschool twice due to the age cutoff for TK), but I honestly don't even know if that's something he'll attend. His school district just put out their plan for reopening this year and I'm really disappointed looking at it. The classes will still hold the same amount of kids (20+), face masks will be required, no field trips, no outside food for birthdays. There's so many changes that preschool won't be the same for him and I can't imagine sending my 4 year old to school like that. How do you even keep that many young kids safe while trying to get them to enjoy being there? 

When this all began my son was in preschool. It was his first year and he was LOVING it. He loved his teachers and all of his friends. He really enjoyed everything they were doing in class and he learned so much. It was only 3 hours a day/5 days a week but it was something for him that was his own outside of his brother and his home. Before preschool he could be really shy and standoffish at times when it came to playing with other kids. Preschool really helped bring him out of his shell. And just like that it was all taken away. His teacher did what she could with Zoom meetings every week to keep the kids in contact while they finished out the year but it was hard for him. Most of the time he wouldn't participate with the class. He would just sit and stare and be really quiet. He's used to FaceTiming his family but I can't imagine how confusing it was for him to see his teachers and classmates on a screen and not in a classroom. When we drive by his school he tells us how much he misses his friends and asks when he can go back. It's really so heartbreaking because we don't have the answers for him.

I feel like I'm robbing him of some of the most crucial times in his life for social interaction and learning but no one is going to protect my kid like his parents. I have to take my momma heart out of it and do what's best for my child but right now I am so confused on what that is.