Can you tell me what ぐらいでいいのでは means? Also, I don't understand why potential form of the verb is used in this sentence Can you help me to translate this sentence?

Can you tell me what ぐらいでいいのでは means? 
Also, I don't understand why potential form of the verb is used in this sentence Can you help me to translate this sentence?

Context: The questioner asked how to eat "elegantly" while you talk to someone, and the responder wrote:

口に運ぶ量を少なめにするといいと思いますよ。三回ぐらい噛んで飲み込めるぐらいでいいのでは？