Anxiety about vague important meeting

I've gone quickly from cautiously optimistic to extremely anxious. After 5 pm on Friday, my boss's boss sent out a calendar invitation for a meeting for our group. I didn't think it was a big deal until I got a direct email asking me to be there in person at a time that I am supposed to be out of the office. It's going to be really inconvenient, so I asked to call in, and he said no, I need to be there in person. I asked my boss if I should be worried. She said she didn't know, but she sounded worried. I tried to find the person who called the meeting, but he was gone, so I didn't have a chance to ask him in person if I should be concerned about my job.

After talking to a couple of other colleagues, here's what we know. They're giving us our official job descriptions next week (which we haven't had for many months now). The person who lays people off will be on vacation next two weeks, so they can't fire me/us (we think). My other colleague who won't be around during that time hasn't received any special instructions. 

Here are my guesses of things that we'll find out at this meeting.

• Probably one or more of my colleague's positions will be eliminated.
• I might lose my half of my employee and she'll be put 100% on her other (clearly more important to the organization) project.
• I might be partially or fully reassigned to a different project (I have no idea what that would be).

Maybe I'll get called into a private meeting before that one and I'll lose my job. Or maybe this won't directly affect me at all. Honestly, I have no idea, and the uncertainty feels really crappy.

Next week I'm going to ESA. Now I don't know if I need to be promoting my project or promoting myself. I really don't want a different job, but if they radically change mine internally then I'll probably start looking. Ugh.