Yes, it will automatically cancel the Verizon account when the port is complete. I have heard horror stories on reddit about failed migrations from Verizon to Visible, but it worked perfectly for me migrating my number from Verizon Prepaid to Visible. The process took minutes. Visible does not have any local stores or phone support and I wouldn't count on chat support, so if you're not comfortable with self service, you might consider a different low cost carrier.
