Really depends on your use case. I personally still run my 17 year old 2.4GHz Core 2 duo with 4GB of RAM as my daily runner. I simply do not hit the walls even on that thing. Most folks here simply would not accept that and not because they are spoilt but their works loads demand more.
Nothing older than Nehalem and Bulldozer got microcode mitigations for Spectre, so I'd say running a C2D online would be a liability by now.