A bit of an offshoot to this thread, but we have lost Zaha, Olise and Eze in the past couple of years, and will definitely lose Guehi, with risk against Wharton, Munoz and Mateta in the forthcoming windows. Wolves have continually sold their best players, and it has got them 2 points from 15 games this season. I acknowledge that Brighton and Brentford have done the same, but to my mind Brentford may still be on a slippery slope. I am always glass half-empty, but we have the potential to get into trouble rapidly if we lose our manager and continue to shed our best players without major replacements. Don't know who we should buy, but the right players are rarely the higher profile ones that most of us know about.
I think you are spot on, other than I don't think it's something we can choose to avoid.
Not to dwell on my previous post but being a key stage, but not the final aim, in the career plans of decent players is something we must accept if we want those decent players to join us. Even if the club doesn't have any financial need to sell, it will be an inherent part of the understanding between club and player that they are here to do a good job for a few years and then they are off to bigger things.
We will see more Geuhi-type situations in the coming years; a good player with a good attitude will give his all for Palace, achieve as much as can be hoped for, show the world how good he is, then have a reasonable expectation of a shot at the big time and decline to let that chance slip through his fingers by signing a new deal with us.
The problem is not so much selling the best player every year, its when players like Mateta, Munoz, Lacroix, Henderson, Mitchell etc look at Olise, Eze, Guehi, and surely Wharton sooner or later, as they all leave to go to the next level, and demand the same. Why shouldn't they? If they stay here and sign long term contracts with us they will probably only regret it, like Zaha so evidently did. Then you get the worst of both worlds, a player not as hungry as he was who has faded a little in his heart, to whom we have committed so big a contract that we have to build the team around him and it limits us financially elsewhere.
In recent years Wolves, Southampton, and Leicester all got into Europe, knew they couldn't hold onto the players who got them there once the big boys came calling, then 'sold well' and trusted they could repeat the process, but ended up soulless, hollowed-out shells who went down with not one functioning heart or pair of bollocks between them. All of them, plus Brighton and Brentford could choose a brilliant XI of the team they could have had if they had kept their best players, but it can't be done.
That's why the OP question is so important: Who is the next wave of players in the cycle? The thing is, whoever they are, I don't think they'll be supplementing the existing core so much as the beginning of replacing it.
I think maybe Price at West Brom, has looked good for Norn Ireland but might be a flash in the pan.
Perhaps Troy Parrott, though only if Mateta leaves and even then he would probably block Nketiah and stop us getting value from him, which we might do if he becomes the main No9.
Jordan James might be one to watch, but no reason to think he's good enough at the moment.
Jay Stansfield at Brum seems promising, I think Fulham rated him, but not enough to pick him.
Hayden Hackney seems the best bet.