in addition to the new features coming in the next version of macOS, to be announced at next months WWDC, there will be some that are retired.
According to developer Steve Troughton-Smith, macOS 10.15 will lose support for a number of features:
32 Bit App Support
Apple has been warning users in High Sierra and Mojave that 32-bit apps will soon no longer be supported. It is expected that the next macOS will be the first to remove support completely.
Carbon is an Apple’s C-based application programming interfaces for macOS. Carbon haas provided a good degree of backward compatibility for programs that ran on Mac OS 8 and 9. Apple has transitioned to Cocoa and with the completion of the transition to 64-bit Carbon apps will not longer run.
Ink Handwriting Recognition
Ink, Apple’s handwriting recognition technology introduced in Mac OS X 10.2 Jaguar. It is rumoured that iPads with Apple Pencils will be able to be used for drawing in the next macOS which may be some comfort to those that utilise this functionality.
QuickTime 7 and QuickTime plugins are also being removed. Applications that take advantage of the technology for media output may also no longer work.
PPTP VPN support is also likely to be removed. macOS Sierra removed PPTP from System Preferences but it was previously still possible with third party software. PPTP is old and insecure so you shouldn’t be using it anyway!
Apple Hardware RAID
Hardware RAID support will also be removed. This only affects long gone Apple RAID hardware that is no longer available. External hardware RAID and software RAID will still be supported.