Currently players who hit level cap waste all the experience points they earn and loose a bit of motivation to play the game. Also one of the perks of buying VIP goes away.
Addition of paragon levels can solve this issue. It serves the same purpose as in diablo3 - give top-level players a sense of progression without making them overpowered. The bonus could be as simple as 1hp per paragon level or smth more elaborate as in diablo3. If level cap is increased the paragon progression can be stopped until new level cap is reached.