Originally Posted by Kapusta

As has been mentioned, you can still stick a tube in there. In fact, you should still carry a tube. I have done that on two occasions on my MTB over the years when I got sidewall rips too big to seal (which would have flattened a tube as well). The only difference is that instead of pulling out a damaged tube, you are dumping out some sealant and removing the tubeless valve.

I have never used a plug, but my friends have on a couple of occasions. Those are really easy. Easier than changing a tube.