I am so tired of the suggestions constantly posted to trade our talented young players. Really liked the comment by one NBA writer this summer after it was clear Anthony Davis was not coming to Boston - the guy said that it is time Boston settled in to find out who they are instead of constantly projecting trade/free agent possibilities to become some future dream.
Remember, Antetokounmpo did not start putting up superstar type numbers until his 4th season.
Our two young J's are starting their 3d and 4th seasons, respectively and Hayward is still recovering from his injury and may even be one more year away from returning to his prime form (see Paul George). Walker is locked in and now we need to develop Rob Williams and add a couple of more pieces. It was Red Auerbach who said that one year is not a very long time to wait to develop a contender. We have a very good young core that have been acquired as part of the rebuild after the Garnett team moved on. Be patient and hope Danny does the same and allows this group to grow up together and remain Celtics. We may well have a few titles to enjoy during their careers.
"...a few titles" - yes. It appears that today's CBA makes it more difficult to build a perennial contender, and the events of Summer 2019 suggest that we might just have crossed the Rubicon in that respect. But multiple titles with a consistent core group still looks possible; Steph, Klay, and Draymond were together for many seasons before they became the juggernaut that kept showing up in the Finals year after year (oh and surely everyone is writing them off too easily for the upcoming season...), and that team was enticing enough to attract a difference-maker like Kevin Durant.
The discipline that the Celtics brass showed in letting Horford go is going to be essential to achieve a perennial contender: “We wanted to keep him. Thought we would keep him. But he got an offer we weren’t comfortable with trying to match ... We were ready to make a bunch of moves to allow us to re-sign Al, but that number wasn’t a number we could do.”
"...a bunch of moves..." - meaning, ultimately, sacrificing a part of the future to win now, unless the price was right. The Sixers went over Boston's walk-away number, and the Celtics, prudently and properly, walked away. People around here are too eager to trade away one or both of The Two Jays; but they're the best bet for the long-term future. It appears that management (perhaps remembering the comment from Red Auerbach that you cited) is willing to "take a step back to take two steps forward".
Philadelphia's approach appears to be in stark contrast to Boston's. Let's keep that in mind as the long-term results roll in in the next 5-8 years.
I think it's worth asking if Jayson and Jaylen aren't in fact best suited to be second and third bananas; it's a question that assumes that you need a #1, #2, and #3 to win a championship - and that might be true, though we might require another century or two of NBA championship teams to get a decent sample size.