It's not a serious injury, but it is one of those nagging injuries.
I expect Embiid to play every game, but the question will be, will he play on a minutes restriction or not? If Embiid is able to play 36+ minutes regularly, then it's a sign he's 100% fine. If not though, then he's probably not 100% and that's a huge advantage to the team facing the Sixers.
We've often seen Embiid have monster games against teams (including us in the playoffs last year), but usually by the 4th quarter he's evidently fatigued and sluggish out there. The Sixers really rely on him and the ball goes through him often (understandably). Adding Butler, Harris and Boban will help but I reckon they'll have to step up if Embiid is truly on a minutes restriction of sorts (just 30-32 minutes/game).
Their depth is fairly thin as is.
I posted in the Playoff Prediction thread, but I predicted PHI in 6 with the assumption that Embiid is not 100%, but if he is, it'll be a series won by PHI in 5 games.