For those who might speed through 18.650, the natural next step is [0] 18.655 (Mathematical Statistics) followed by the new course [1] 9.521 (Non-Asymptotic Perspectives in Statistics).

[0] https://ocw.mit.edu/courses/mathematics/18-655-mathematical-...

[1] http://www-math.mit.edu/~rigollet/IDS160/notes.html