An addition to ChangeWave’s July survey suggests that nearly one-third of U.S. iPhone 4 users would be likely to switch to Verizon as their service provider should the carrier begin offering the iPhone. 18% of iPhone 4 users said they would be “somewhat likely” to switch, while 13% said they would be “very likely” to switch. Notably, the survey results shared earlier this month indicated that the requirement of using…