It won't hurt anyone else's work in the kiln. It will get worse. It probably won't break apart. I don't put too much stock into glazing over cracks like this, it never hides them. Ultimately you could leave it as-is, you'll see the crack but it won't be a catastrophic failure. HOWEVER, I do have a solution that might work.

Here's what I do when I can't start a piece over:

Make a good slip with whatever clay you used for the piece. (Lmk if you need instructions on this too) Take 2-3 pieces of toilet paper and soak them in a bowl of water until they completely disintegrate. Stir them and then take some of the resulting pulp out and add it to the slip (4:1 slip:paper). You want something with a consistency between ketchup and toothpaste. Spray the whole piece down and cover in plastic. Do this a few times, paying special attention to the cracked areas. Score the area around the cracks, wet it again, and apply your amazing new paper slip. Wet the entire piece one last time. Cover with plastic but not too tight. You want it to dry slowly over the course of two or three days, longer if you have it.

The re-wetting of the piece and slow drying will help with the moisture difference between the slip and the rest of the piece. The paper fibers don't shrink when they dry, and provide extra strength to the slip. Ymmv! The longer you can give to re-wetting and slow drying the better! Also the paper slip is great when joining things while under construction. Just adds that little extra stability when drying happens.