Say I was to buy the new IPhone coming out roughly in September and I go onto a plan. The following year (2020) I decide I want to upgrade to the new IPhone. Will there be an option where I can upgrade to a new plan for $99.
Seeing as lease plans are no longer being offered (including to current lease holders wanting to upgrade at 12 months) you go on a plan where you own the device.
Curerently you can pay $149 at 12 months to recontract again (if your device isnt damaged).
Optus have somewhat corrupted the term "leasing". At Optus the ability to upgrade your phone to a new one for a nominal fee (in this case its now $149) every 12 months is built into every plan (leasing and non leasing). Just click on the CIS for any plan/phone you are interested in and read the Flex Upgrade portion to confiem.