What could happen to my conditional green card if the EB-5 project fails?

Until and unless USCIS issues a decision/denial, your status is not affected. If the jobs were created and the money was invested properly at the time of filing I-829, unless USCIS issues an RFE which you can''t respond to due to the failed project, you should be fine. Another option is to redeploy the funds.

If the jobs are not created, the I-829 can be denied.

In some cases, you can redeploy funds.

As long as your I-829 petition is pending, you remain a conditional lawful permanent resident. If the I-829 is denied, you can seek a review of the denial and a review of any other available relief in removal proceedings before an immigration judge. During your removal proceedings, you can stay in the United States legally and work.

You can stay in the U.S. until a judge orders you to be removed. However, you should act now to protect your rights.

What is likely to happen is that the I-829 would be denied, and status would end.

You should wait until you officially hear about the project. Even then, you may be able to file an appeal of the denial to your I-829. So, consider staying put for a while as your case winds through the legal challenge that you are entitled to deploy.

If it fails, USCIS will not remove the condition from your status and your status will end.