Jayson Tatum possibly being unhappy is not a problem for 2019, it's a problem for 2026, when he's coming off the five-deal restricted-free-agent deal he signs following his rookie deal, and he's an unrestricted free agent for the first time. Until then, I'm not sure I'd be worried.
This is the value of first round picks. If you land a superstar, you can lock them into your team for about the first decade of their career, assuming they're worth max money.