Long-run Equilibrium in Monopolistic Competition:

The short-run super normal profit will attract new firms to the product group since there is no entry barrier (if in short run firms are incurring loss, they will quit).

If more firms enter the product group, the proportionate demand curve will shift to the left and would become steeper. This will continue till all the profit is wiped out.

The long run equilibrium is depicted in the following figure:   

Each firm in the equilibrium (X_e, MR_f, P_e) maximises its profit (MR_f = LRMC) and since LRAC is tangent to D_f, there is no supernormal profit. Therefore, there will be no entry or exit. Since (X_e, P_e) lies on D_p, the market will clear.