Crampons might be usefull some years on June 15th, but would be unlikely this year. The snow is melting too fast for that to happen. Usually by then the remaining snow on the trail is well packed down and easy to travel during the warmer parts of the day.
They do rent crampons in Lone Pine Sporting goods in downtown Lone Pine.
As it gets closer, you will have a better idea about the snow. Based on what I saw up there last week, I would really doubt you would need them this year on June 15th