Are the wheels coming off the cart? Historically things fall apart slowly at first, and then all of a sudden. Some folks are surprised by the suddeness, not noticing the slow build up. It seems to me that the club has over-reached that which, given its resources, it is capable of successfully achieving. Which is competing at the highest level in the league and in Europe, and in two domestic cup competitions.
Although the club is reliant on the sale of quality players the loss of both Eze and Olise in quick succession has left an attacking hole not yet filled. This is becoming apparent as the season progresses and many chances are missed. Things don't happen immediately, pieces are patiently put in place for the whole picture to emerge, and conversely its the same when pieces are taken away and not replaced, slowly but surely things deteriorate.
Oliver Glasner will leave, Parish will appoint someone else. Palace will find its own level, which in recent years has been between 12th and 14th. Most of the current first 11 will leave, Parish cashing in whilst the going is good.
Enjoy it while you can.