What Would Have Happened If Obi-Wan Was The One To Arrest Palpatine?
The attempted arresting of Chancellor, later Emperor, Palpatine by the Jedi Council is one of the most important moments in Revenge of the Sith and the Star Wars universe as a whole. In a lot of ways, it was the last chance the Jedi had to stop Darth Sidious, and it also served as the moment that seals Anakin's fall to the Dark Side and Sidious' victory over the Jedi. Mace Windu, Kit Fisto, Agen Kolar, and Saesee Tiin arrived at the Chancellor's office to arrest the secret Sith Lord, but unfortunately, Sidious proved to be too powerful for the Jedi Masters. Aided by Anakin Skywalker, soon to be Darth Vader, Darth Sidious killed all the Jedi Masters sent to arrest him.
But what would have happened if Obi-Wan had been one of the masters sent to arrest the Chancellor or even lead the group? Obviously, I know it is a completely "What if?" scenario, but I think it is a fun thought. It also helps to show the gravity and impact of that scene for Star Wars as a whole.
As I said above, the reason that scene is so instrumental to Star Wars is because it cements Anakin's fall to the Dark Side, the utter failure and defeat of the Jedi, Darth Sidious' victory, and the rise of the Galactic Empire. In order to explain what effect Obi-Wan would have on the scenario, I have to explain why this scene is so important. Sidious kills all but one of the Jedi Masters sent to take him, which is Mace Windu, who is almost able to defeat Sidious but is stopped by Anakin Skywalker before he can strike the final blow against the Chancellor. The entire movie has been setting up Anakin's conflict with the Jedi Code and his struggle with turning to the Dark Side.
At the beginning of the film, Anakin killed Count Dooku because Palpatine told him that he is "too dangerous to be left alive," and Anakin regretted it because it wasn't the Jedi way. Then in the arrest scene, Mace Windu said the same thing about Sidious. This was basically the straw that broke the camel's back for Anakin. He felt at this point that the Jedi and the Sith were both obsessed with power and wanted to do what was in their own best interest rather than what was fair. Anakin believed that, if they were the same, he might as well go with the ones who were going to save his wife. Out of desperation, he turned on Windu and saved Sidious. Then he crossed fully to the Dark Side and became Darth Vader. CinemaWins goes into much more detail on this, and I highly recommend you check it out to see how this scene affects the whole movie and Star Wars in general.
How does this relate to the original "What if?" question? Well, Mace Windu and Anakin were obviously not as close as Obi-Wan and Anakin were. I think, had Obi-Wan been in the situation, he may have been more likely to take Sidious into custody, or he would have attempted to anyway. At the very least, he could have explained to Anakin why Sidious had to be destroyed. However, Sidious would likely not have given him a chance in the battle, and he could have proven too powerful for Obi-Wan. I would like to think that Obi-Wan might have been able to better demonstrate the need to defeat Sidious then and there, but it would probably be more accurate to say that Obi-Wan would have been killed.
Obi-Wan's death could have turned Anakin against Palpatine for good, but there is no guarantee that he wouldn't have become the new Emperor if he killed Palpatine in his anger. On the other hand, Obi-Wan could have helped Anakin with his inner turmoil. This could have been Obi-Wan's chance to redeem himself of his failures as Anakin's teacher and set the Jedi back on the correct path. If Obi-Wan had gone instead of Mace, there is the possibility that the Sith could have been defeated once and for all, and balance could have been achieved in the Force.
Of course, if any one thing went wrong and Obi-Wan died, there would be no Luke trained as a Jedi, and the bad guys would have won. Conversely, if there is no Darth Vader, there is no Star Wars, and we would have probably gotten one of those "Time Paradox" messages from Metal Gear Solid 3. However, I think Palpatine knew all of this. I am not saying he planned for every little detail, but he did lead two sides of a war and hide from the Jedi in plain sight. He obviously had a knack for planning. I think he made sure that every piece fell where he wanted it to in the grand scheme, and he may have even initially lost to Mace Windu on purpose to make sure Anakin fell to the Dark Side.
Either way, it is a testament to how important that scene is in Revenge of the Sith, and it shows how much one little change could impact the entire universe. Of course, it is all speculation, but is is fun to think about. In the end, everything worked out how it was intended.