When I see teams like the Bobcats, Wizards and Raptors flourishing in the EC, I can't imagine raking up 40-45 wins in the East is going to be difficult.
I don't think you're really giving these teams enough credit.
The Raptors had two All-Star caliber players this season in Lowry and Derozan. Valanciunas and Amir Johnson is an underrated defensive frontcourt.
The Bobcats had Big Al -- second most valuable big man in the Eastern Conference behind Joakim Noah.
The Wizards had John Wall (best season yet), Gortat (very nice as always), and Beal (deadly high usage shooter).
It'll be hard for the Celtics to beat Atlanta's trio of Teague - Millsap - Horford next season, too, if they're all healthy.
These teams have quality players. Unless Rondo totally returns to form next season -- and then some -- or one of the young guys for the Celtics takes a leap to All-Star status, there's a good chance the Cs are inferior to all of those teams next season, even if they trade for Sanders / Asik.