Short answer: no idea. Long answer below from a software engineer's persective:
There are effectively two types of companies out there: those that are proactive; and those that are reactive.
For example, if a company creates hardware requiring drivers, it's best if that company works with the pre-release versions of the operating systems to work out any issues. Or, in the Apple Silicon case, to have obtained Apple's hardware DTK (developer transition kit). In this manner, the company can work out issues before public releases.
Along with that though is the concept of longevity. Say a printer came out in 2015. At that time, the drivers should have all been 64-bit Intel. It shouldn't take too long to transition to Apple Silicon. However, would companies such as Canon choose to not port the software for older hardware?
As of now, I think printer drivers will be emulated via Apple's Rosetta2 technology. This technology should at least be around for another two years and perhaps a year or two beyond that. Once Apple's entire lineup of Macs are on Apple Silicon, they will start to phase out support of Intel-based Macs. And, by extension, companies maintaining the Intel-based solutions will slowly drop support of that firmware/software over the years.
Going forward, I would hope that Canon creates all their software as Universal (Apple Silicon plus Intel). Then, when the time comes, just provide Apple Silicon.
This is no different that all of the past architecture transitions: For hardware, this was 68K to PowerPC, PowerPC to Intel, and now Intel to Apple Silicon. Or 32-bit to 64-bit. Or the older CFM app binaries to mach-o binaries. In all cases, Apple has provided the ability to create "Universal apps" and thus have allowed folks the best possible transition.
Still, there are indeed companies that refuse to embrace the new architectures. I definitely do not see Canon going that route. But I do hope they step up their game to be more proactive.
i am looking for a similar answer to the same problem.. but i do know that apple seeded the hardware and OS almost a year ago, why the delay for just simple drivers in unknown...
as far as for printers, i know that some of the printers regardless of whether there is thrid party drivers are bundled into the OS native already and any additional software, like for a scanner, may work in rosetta, at least it did for epson printers.