The scariest part is that he didn't start playing basketball until 15 so there are very few miles on his body and already these types of significant injuries don't look good for Embiid, I would be interested to know if these are impact or non-impact injuries as non-impact would be more his natural biomechanics which could be career threatening.
Embiid was a volleyball player with professional aspirations before he switched to basketball so not as few a miles as you would think.
Embiid did hyperextended his knee during the Portland game. After doing so, he was checked out, allowed to return to the game and suffered a subsequent fall. He sat 3 games but then was allowed to play in the nationally televised Houston game playing 28 minutes without any apparent issues. Afterwards he's been experiencing knee swelling.
Hard to know what is actually going on. They've said Embiid's knee injury is a bone bruise and slight meniscus tear which shouldn't be that bad. However the Sixers FO have no credibility. With Embiid, Simmons, Okafor and Noel's injuries, their statements and projections haven't matched reality.
I tend to think this setback isn't that significant. However if they actually have serious concerns about Embiid's long term health, Colangelo was a complete idiot for trading Noel for relatively little. Paying Noel 4yr/80M to be a backup wouldn't have been optimal but it looks like it may have been prudent.