You’re now the Mavs’ GM. What are you going to build?

[Dahlsim]

If I’m the GM, I’m looking to get 2 players to add to Flagg, PJW and Lively to be my core dynasty group. Those 2 names are Anthony Black and Cason Wallace. I’d have little problem using any available assets (other than the names listed) to do so! I think a lineup of Wallace/Black/Flagg/PJW/Lively kills for many many years!

Nice.  That model involves finding the sweet spot of trading veteran stars to get the roster younger before the stars completely age out of their asset value in the eyes of the NBA trade market. 
Remember Danny Ainge and the Celtics pulled this off to perfection: 
https://celticswire.usatoday.com/story/s...473674007/ 

On this day in Boston Celtics history, the storied franchise dealt away the remainder of the Banner 17 title team in 2013. The Celtics traded big man Kevin Garnett, forward Paul Pierce, guard Jason Terry, and forward D.J. White to the Brooklyn Nets in exchange for forwards Gerald Wallace and Kris Humphries, wing Keith Bogans, guard MarShon Brooks, forward Kris Joseph.
The deal would also include three future first-round draft picks and the right to swap first-round picks in the 2017 NBA draft. The move put an end to a 15-season career with the team for Pierce, and six for Garnett: Terry and White had played just one season each with Boston.
One of the most lopsided trades in NBA history, the Celtics would begin using the haul to rebuild immediately. Only out of the playoffs for a single season, team president at that time Danny Ainge pulled off one of the better jobs rebuilding a program after its core aged out in modern league memory.

Of course the Mavs situation is different but the basic idea is unloading veteran stars before they age out.  This would require the players show some ability to maintain health and some team(s) believe they have enough left to help their current hopes.  

Houston for example just aged up to a 36 year old Kevin Durant while Phoenix reloaded and got younger.