I believe this is a temporary problem-- that degree of warping is just mild and fairly simple geometrical transformation.
When will alphanumeric captchas become useless?
If the usual captchas are useless, one solution is to go to simple semantic captchas. I've seen a few of those which require answering a very simple arithmetic problem or figuring that "What is the opposite of hot?" isn't a trick question.
Are there other possibilities? Will the reverse Turing test (machines recognizing people) continue to be reliably solvable?