Stephen Hackett has a list of the Intel Macs that MacOS 26 Tahoe supports, and the ones they’re dropping support for this year.

Apple has gone through three CPU architecture transitions in the Mac’s history:

• 68K to PowerPC starting in 1994
• PowerPC to Intel starting in 2006
• Intel to Apple Silicon, starting 2020

With the 68K–PowerPC transition, they supported 68K Macs through Mac OS 8.1, which was released in January 1998. With the PowerPC–Intel transition, they only supported PowerPC Macs for two Mac OS X versions, Mac OS X 10.4 Tiger (which initially shipped PowerPC-only in 2005) and 10.5 Leopard in October 2007. The next release, 10.6 Snow Leopard in August 2009, was Intel-only. (Mac OS X dropped to a roughly two-year big-release schedule during the initial years after the iPhone, when the company prioritized engineering resources on iOS. It’s easy to take for granted that today’s Apple has every single platform on an annual cadence.)

With next year’s version going Apple Silicon-only, they’ll have supported Intel Macs for five major MacOS releases after the debut of the first Apple Silicon Macs. I think that’s about the best anyone could have hoped for.