There is two ways to dream about how good BOS can be. In addition to dreaming about players on other teams that we may be able to get, you can also dream about how good some of our young players could become. Hugo and Cenac are the two that have the most potential in my mind. I see solid starter potential in both, maybe Hugo and Cenac are a future Derrick White and Al Horford level pair.
As to trades or backfilling Paul George's salary after he is gone, there are two ways to look at that. One is to go out and get another max guy to pair with Tatum. I don't think that is the way to go anymore, unless you can get a player like Giannis. More likely, you backfill the +/- $60M with two players at $30M each or $40M and $20M, or something like that.
As to trades, it would have to be something like George and picks for some combination of players. The cap restrictions would work as we would have PG's salary outgoing. I am not sure there are going to be a lot of options to trade Paul George. The other option is to let his contract expire and then try to sign someone to backfill. The problem with that is we would need cap space or an exemption or something to be able to offer anyone anything more than the MLE. I have not done the math to see how much cap space BOS will have in the 2028 off seasons, after PG's contract comes off the books, but it may not be possible to sign on someone at $60M to replace him. It will depend on what other contracts are on the books at that time.