So says ESPN:

The more we’ve learned about Embiid’s max extension, the better it looks for the player. One of the contractually agreed upon injuries would have to be career-ending or at least career-threatening to convince the 76ers to waive Embiid and reduce the money he’s guaranteed over the final four seasons of the contract. If there’s any hope of getting Embiid back after a severe injury that is covered by the contract, the Sixers still owe him so much money that it will probably make more sense to try to get him back on the court rather than waive him.

The other concession from Embiid’s side in negotiations is that he is only eligible for the supermax (starting at 30 percent of the cap instead of 25 percent, which would push the value of the extension to $176 million) if he’s named to the All-NBA First Team or voted MVP this season, limiting the risk to Philly that Embiid is healthy enough to sneak onto the All-NBA Third Team because there are few candidates at center:

http://www.espn.com/nba/insider/story/_/id/21070287/kevin-pelton-joel-embiid-extension-gordon-hayward-injury-more-nba-news