No one knows if there will be a software update for the current M1 devices (I doubt so), but you can be sure the next MacBooks will support 2 external displays. At least the more expensive ones.
I, for one, will not be getting an AS device until and unless it can support multiple monitors. This is a minimum requirement for computer functionality in the year 2021.
Although not confirmed officially, almost certainly. At worst, it will be like the Mac Mini (support two monitors via USB-C and HDMI - might be why that port is being reintroduced?).
Agree with others - while it's not 100% confirmed, I think it's virtually certain. It would be insane for their higher-end MBPs (14" and 16") to not support dual monitors, and would be a glaring disadvantage / issue in Apple's move away from Intel.
Although we don't know if it will happen, Apple has to make it happen. They can get away with it on the base models but on the actual Pro models it is a minimum requirement in my opinion. Even on the base models they can only get away with it because they are first gen. The second gen base models need to have support for multiple displays too.