At this point it seems unlikely that Japan will open it's borders for tourists this year, but I still haven't cancelled my flights yet. I've been holding on to the slim chance I could go, but it's pretty much certain now that it won't be possible.I'm still going to wait a month or so before cancelling just in case a miracle happened.
I've only been to Mirai yearly since 2017, but I can kind of understand where you're coming from. I'm not really sad about Magical Mirai happening this year, I'm just sad I (most likely) can't be there and there's nothing I can do to help. If Japan won't let me in in the first place, there's no workaround to that.
If there's anything positive about the situation, at least I have a lot bigger budget for Mirai 2021 (not that budget's really been a problem before though, I've always made sure to have enough to cover all expenses at the event, like buying all the merch I want). At least I could stay in a "proper" hotel next time instead of the cheapest business hotels.