It's unlikely they'll follow the path they took last season. This will be a very different team compared to last year. I honestly also think Chelsea can do very well and even an Italian team could make a great surprise, and it could be Juventus.
Many teams struggle at the start of the season, and that's normal. But defending the UCL title is different. Most of last season's champions struggled more often in the UCL, making it impossible for them to defend their title. This isn't a myth, but a fact. So far, only Real Madrid has successfully defended their UCL title. The worry is that after winning, some player feel their target already achieved, so it's like someone who said "keep trying your best but if you can't be the champion, the important thing is that you tried". I hope I'm wrong, and PSG makes an epic comeback.