It already shows it has the ability to be upgraded, Apple pay (Apple's watch and iPhone 6) are compatible with the system and it took no hardware to do that... The infrastructure is there and set, something other parks do not have including other Disney Parks and has he stated in the interview at the end of the article something they are looking at at all the parks because it is the future... Generally speaking once a company goes through this painful of a tech upgrade they never want to do it again so they staggered upgrades to avoid it... So we will most likely always be seeing them upgrade and replace WiFi Access points, adding fiber, replacing computers and server functionality. If they plan it correctly now they will not need to do massive upgrades again, they just always need to keep the current infrastructure upgraded and current so the projects stay manageable.
That is just my experience in I.T. I know Disney is much smarter than me with large project planning and budgeting, my only experiences is with companies up to 500 employees but that is how it SHOULD be handled lol...