Counterargument, for the fun of debate: What happens at the end of that 2–3 years? The Raptors currently have a nice collection of young talent on their bench. I love Norman Powell. Bebe is a good rotational center. Cory Joseph is exciting. Pascal Siakam is a energy big. All down the line, they have solid talent. But none of them have star qualities, in my opinion. They will also soon all become expensive. Bebe, Powell, and Caboclo are restricted free-agents in 2019.
It’s realistic the team would make 2–3 more strong runs by keeping the core, and seeing the youth develop. But when 2–3 years is up, and you maybe don’t have a single Finals appearance to show for it, where is your team? Lowry is a 34-year-old $40 million point guard. DeRozan is a 30-year-old unrestricted free-agent in 2020.
If you decide to retool or rebuild then, their value is diminished, and therefore your ability to maximize a return is inhibited unless a team is really desperate for a guy about to be a free-agent (DeRozan) and an aging point guard (Lowry).
However, if you decide to retool or rebuild prior to the 2018 trade deadline, you maximize a return, can still have a competitive team because your young core has talent, and you can infuse top talent through two loaded draft classes in 2017 and 2018. Then, hopefully by 2020, the Raptors are ascending to an even higher level than it is today.
The risks go without saying. The young talent you draft may become busts (like Anthony Bennett). They may become blossoming stars that get hurt (like Joel Embiid). But I think Masai Ujiri is a unique talent evaluator and his track record of nailing draft picks and winning trades would bode well.