I have never considered that way of squad building. But it's certainly intriguing, the point you make.
Usually, as I have noticed, the elite coaches, keep the spine of the team and build around it every few years.
Your way seems like it could be the right way to build. A total of three players for each position, one in his prime, one up & coming and one youngster on the side.
One question I have though is of mentality and motivation. Let's say a team that plans it's future in this way and is picking up trophies. What motivates these young players after they have won a lot. We have seen how Barca seem to suffer a lack of motivation after a few years of dominance.
United lost that motivation also after a few years of dominance. But Fergusons way of planning was building a team around his few trusted players after every 3-5 years. He could keep on motivating the new players.
I would like to know your opinion on this. Few people give motivation any importance, but in my mind it's as important as tactics and technical & individual brilliance.
I agree with you on how elite coaches usually build the squad, and of course squads constantly evolve and change for a host of reasons, contract issues, lack of opportunities etc, personal problems etc. As such they will always need tweaking every few years, but with the age profile of the squad as it is, there is clear continuation in a couple of positions, especially in midfield as I said.
Motivation shouldn't be a problem under Klopp, or any elite coach for that matter, even after success, I'd say the examples you used all stayed very motivated, hence why they won so many trophies together. The problems arose after the retirements of key players who hadn't been replaced with the same quality. Even for us, it's taken a while for us to truly replace legends like Carra and Gerrard, but I do think that Oxlade-Chamberlain does serve as a perfect age fit between Lallana and Woodburn. And all three are of the right quality. Of course we have hit lucky with those three, Lallana was here before Klopp and Woodburn is a massive bonus as hes came up from the academy.
If anything, I think the only problem that arises when trying to build a continuous squad is getting the right amount of minutes on the pitch for the young player. It's a problem that all the big teams are encountering; Untd lost Pogba and Michael Keane for pittance because they couldn't get them on the pitch. City have just lost Sancho who is a big talent because he knew he wouldn't get a look in. Chelsea have loaned so many out year on year that it's now to their detriment, players are starting to say no ta, I'd rather go elsewhere (Liverpool!!) Where I might get a chance to play.
Motivation and man management is Klopp's thing. I'm trying to recall our biggest loss under him, and I'm struggling to recall a battering like what we dished out at the weekend. Europa League final vs Sevilla is probably as bad as it gets, on any given day less than 100% effort will be ruthlessly punished by Jurgen. It's why Sakho is now at Palace.