Cyberpunk 2077's subplots will change the main story in such a way that you may not even have to finish the main story but can still complete the game, Pawel Sasko, Lead Quest Designer on the game said in the latest interview.
Cyberpunk 2077's main story may be shorter than The Witcher 3 but that does not mean it will lack quality content. Pawel Sasko, Cyberpunk 2077 Lead Quest Designer on the game mentioned how CD Projekt Red wanted to avoid the issue of a stretched out story with Cyberpunk 2077 so that's why they have a shorter main story but more subplots that can influence the main storyline in various ways.
These subplots can change the main plot of the game in such a way that players may not even finish the main story but still finish the game. Judging by this, it is possible that some side quests may lead to a complete change of location or the death of an important character that has a part to play in the main story.
Here's the important bit from Sasko's interview:
"So in the Cyberpunk's structure we have this wheat spike, which serves as it's center, the main storyline with different subplots surrounding it, which can be triggered in a various ways. Those subplots allow us to do something that we have never done before, they change the main plot of the game and they are doing that in such a way that you may not even finish the main plot, but still finish the game and get a completely different epilogue then the player with a different lifepath who made different choices, met different characters and formed relationships with them."
It is safe to say that this sounds incredibly exciting and opens up a ton of options and different scenarios, allowing players the freedom to take on the story as they please.
On top of this, it looks like CD Projekt Red will continue to offer memorable stores via side quests, which was one of the highlights of The Witcher 3: Wild Hunt. Cyberpunk 2077 is certainly shaping up to be one of the biggest, if not the biggest game of the current generation and we cannot wait to finally start exploring the iconic Night City.