I will reserve judgement until I see precisely who he intends to replace them with.
His adoption by a lot of centrist Dems, and his absorption and placement as DNC Vice Chair makes me wonder if he's just the Centrist Dems' vehicle to remain the top influence in the party by replacing old Centrists with young Centrists.
Edit: To clarify for anyone else who is confused, I really hope he does what he says he will! We need lots more young progressives.