The general public would go bonkers,
Me personally, I don't know. for a period of time I only used what would be considered antiques in the computer biz.
I relied on a crappy laptop with only 4GB of HDD space, 256MB of RAM, and a 400MHz Celeron. This was back when I could squeak by on the web with Opera 10 or 11. I had the bare minimum on it. I had offbyone browser (for when opera was too slow), I had an MP3/OGG player called "billy", and a word processor called "Atlantis". Not much for games other than an NES emulator and Doom. OS was Win2k.
Sometime in 2011 or so I managed to get a hold of an old Dell and upgraded the thing to the max with 512MB of RAM, some kind of Radeon (PCI only) with about 1GB of vram, and shoved a 1.4GHz Pentium 3-S into it. It stuttered here and there, youtube and the like had to be put in low quality for best results, but for the most part it worked.
Then I later restored another old Dell, this one from 2004, I put in a P4 Extreme, a Radeon HD 4750 and 4GB of RAM (only 3.2 usable), I used that until XP lost support. (Had I known about the unofficial POS 2009 updates I'd probably still be using the beast.)
So I don't know how far back I would willingly go, I wasn't using those machines for nostalgia, but because it was either that or not computer at all. I do know that an average user would not be able to adapt because I had to specifically get hardware and software to fit my needs. If I just used the standard bloaty stuff the general public used at the original hardware specs, none of those machines would have been usable.