Looks like Universal is not giving up on using AR on Mario Kart. A patent published this month specifically describes how the AR/VR elements of a ride system could be updated and upgraded without "significant attraction downtime".
...It is also now recognized that it may be desirable to provide attraction features that readily allow upgrades, maintenance, or replacement of key components in a manner that does not create significant attraction downtime. Indeed, as one example, theme park attractions using ride vehicles have historically had long lead times associated with technical refresh upgrades. Thus, cutting edge technology (e.g., augmented or virtual reality) within these attractions can easily be outpaced by what is available in home consumer products.
Seems to me like they're building in a way to update the AR programming and technology without having to close the attraction. So, it might open with a somewhat crude version, but get better over the years. Kind of like being able to have upgraded Spider-Man to 4K without even closing it.
But, that's just my interpretation. No way of knowing exactly what this patent is for, if anything.
Full patent here, (although it was just posted publicly today so is still missing images and some data):
WO2020068977A1 - Modular augmented and virtual reality ride attraction - Google Patents