That week will be moderately busy, but not tragic and generally not subject to turnstile closures due to overcrowding. There will be lines, you will need a Fastpass strategy, you will need to prioritize your time and objectives, but as long as you do that you'll be fine.
Much bigger crowds and possible phased closures of the park are possible on Saturday the 21st, but more likely from Sunday the 22nd through Wednesday the 25th when Annual Passes are not blocked out.
Attendance and crowds decline dramatically on Thanksgiving and the Friday/Saturday after Thanksgiving due to massive AP and Cast Member blockouts. Huge crowds return on the Sunday after Thanksgiving when the AP blockouts are lifted.