Re: Old iPhones.
My old gaming rig is a Ivy Bridge i7 3770K (the fastest LGA1155 socketed chip you could get at the time if I remember correctly). It had an 4 core 4 thread i5 when I first built it, but got the 'top-end' i7 as prices dropped when Haswell was launched, figuring it was cheaper than a switch to Haswell (so 2013 I think), and would likely last me a few years with just a CPU upgrade. Which it did.
I happily used that as my main gaming rig till last year. I only replaced the i7 system at the back end of last summer, as Ryzen Zen 2 stock levels started to stabilise.
More and more titles wouldn't run on the i7 rig in Ultra/High (at acceptable framerates). With medium settings (or High with some tweaking), becoming the normal setting for me to maintain at least over 40pfs (I'm not one of these that needs to maintain 120fps+, I'm happy with 60, or even down to 40 for single player stuff). But I do play on 1440p or higher.
I also noticed the CPU was becoming more of a bottleneck (even after an OC), as game engines were updated to (finally!) take advantage of more cores, so the CPU was regularly running at 95%+ utilisation in some titles, with my GFX card sometimes dropping to 90% or less utilisation as the CPU was no longer fast enough to keep up. But this was only for a few titles using more modern engines, with older games and engines still being mostly fine.
This of course would get worse over time, but that's just core count, rather than any fundamental issue with Ivy Bridge itself. I suspect anyone using an old Ivy Bridge i7 6 core, such as the Extreme edition (needed an LGA2011, hence me sticking with the 4 core ship on my existing LGA1155 board), will probably still have a machine that runs modern titles perfectly fine.
The days of the Ivy Bridge i7 3770K being a hard core gaming system may now be coming to a close, but it was a good run, and as a general productivity device, it's still quite nippy compared to many new 4 core systems out there.