3 year old using sippies as a binky updated

My son turns 3 in September and I have noticed as of lately he has became very attached to sippy cups he always has one in his mouth even when they are empty. I will have him put them in the sink in hopes he will not want one for a while but he will soon start crying for one. It's like he always wants one! I have been feeling with water more and diluting juice with water. Open cups just don't work for him yet. I mean he can drink from them just fine but 99% of the time he pours them out and asks for a sippy. Any advice? Any one experience this before? Is this normal? Haha he broke himself of a binky when he was 4 months old!! And he let go of bottles with out a fuss! Haha so I am not use to this I have had it easy. So far I am finding this is the hardest stage with potty training and his obsession over sippy cups.

UPDATE ... Doing it! Throwing out sippies this weekend! Soft straw cups for now on..