The last released Macs that were not 64-bit use Intel Core Solo or Intel Core Duo processors, and those haven't been able to upgrade past Mac OS X 10.6 Snow Leopard, released over a decade ago in 2009. According to Apple's definitions of "vintage" and "obsolete", this puts these Macs well into the "obsolete" category.

The upside to removing 32-bit is shrinking the size of the system, removing complexity, shrinking the testing matrix when modifying system frameworks, etc.

The writing has been on the wall for 32-bit apps for a long time, including warning users when launching a 32-bit app that it would cease working, and showing users a list of incompatible software when upgrading to Catalina. App developers were incentivized to release updates to their apps (using 64-bit toolchains that have been available since 2007 and before), and users were given warnings about upgrading if they need 32-bit compatibility.

Meanwhile, over the past decade there has been significant improvement in virtualization technologies, which allow you to run 32-bit operating systems with great performance. You can run Windows XP in a VM or WINE in a Docker container (which runs inside a Linux VM on macOS).