When will High Sierra support end?
For the first time since "Late 2009" my iMac 27" 2.8G has been boxed out of an OS update. It boots in 28 seconds with the SSD I've installed (only repair) but original graphics card (ATI Radeon HD 4850 512 MB) it isn't snappy enough for Apple code it in to Mojave. High Sierra and any further security updates have a predictable end of support which would be when the second macOS update beyond Mojave rolls out.
Based on past Apple trends when will be the earliest Apple Users could expect to loose High Sierra support?
iMac, macOS High Sierra (10.13.6), 27" (Late 2009) 2.8G i7