Yes people have guessed this before, and it's a logical move if you think about it. All IRCC cares about is meeting annual targets. So right now, they'll focus on producing as many PPRs as they can in the remainder of 2021. Completed apps (FSW, CEC, PNP, everything) will get preference, which means expired CoPRs will get priority. Working on apps in their earlier steps will lose IRCC time.
My guess is, if one's app is all stages passed or all stages passed except security but with initiated security, they'll surely land this year. All stages passed with uninitiated security will most likely land in Q1 2022. And the rest will land later. Is that really a problem though? You'll land 2-3 months later than you normally would, that's not the end of the world.