I think these will do a lot better than the core duos.
The Core duos were an unfortunate thing for Apple, they were unfortunately not 64 bit capable and apple needed to switch ASAP. In an ideal world they would have gone straight to the Core 2, but it wasn't available.
The next platform from intel, core 2 WAS 64 bit capable, but Apple needed to switch from PowerPC urgently as there was simply nothing capable that would run in a laptop. If they didn't get something competitive "yesterday" they would have bled so many more sales the Mac would maybe have died. The Core cpu was not ideal but it was much better than what they had available in the PowerPC line-up for portables - and portables are/were the bulk of their sales.
But as Apple (and everyone else to be honest, anywhere cost wasn't the #1 concern) were really wanting OFF 32 bit as soon as possible (for various reasons: larger memory space, better security, better throughput on 64 bit code due to larger/more registers, etc. - all these things were pending due to the size of applications, new network security concerns, etc.), the core machines were prevented from moving forward.
This time: things are different. there's no major upcoming architecture shift required that the M1 isn't capable of, and Apple has had the ability to design exactly what they want, rather than bodge something "good enough for now" in there.
I think the M1 machines will get the standard life cycle of any other regular Apple device. It's not like the M1 is their first processor - they've been building their own processors for 10 years or so at this point, and the M1 is the result of what they've learned during that time in the iPad, iPhone, etc.. It's built specifically for purpose.