Is the final season of Agents of SHIELD a more difficult mission than Avengers Endgame?
It could be.
Instead of just recovering Infinity Stones, they have to stop the Chronicoms (or Chrons for short) , who figured out changing the past to conquer the Earth may be genius. SHIELD also has to make sure it doesn’t change the past too much, or the result will be worse than what Marty McFly dealt with in Back To The Future II.
And what if LMD Phil gets hacked?
If SHIELD wins here, they should be Avengers automatically.
However, they’ll also have to do something that is necessary.

SPOILERS BELOW

The premiere includes a 1930’s style opening credits card, which was a nice touch. Anyway, the Chrons want to take over the Earth, and making sure SHIELD never exists will guarantee that. Their first step is erasing some cops, literally, so they can infiltrate another event.

Meanwhile, the agents try to get LMD Phil up to speed. Before that, Mack and Daisy wonder if they need him. Daisy pushing the button that activates him shows she wants Phil back in any form. Clark Gregg does a fine job in showing how an LMD reboots itself, and admits he’s reluctant being the replacement of a beloved agent. It isn’t long, though, before he becomes the Phil Coulson we all know when he comments he’s been through the worst “This Is Your Life” ever. He also proves to be more skilled in dealing with guys with guns. We’d rather have this guy than Sarge.

Fitz is not in the episode, because Simmons is worried the Chrons will scan his brain and figure out what SHIELD’s doing. They want to alter certain details in order to erase SHIELD from existence. They already have Fury’s Black Box, which has all the secrets. It’s likely Fitz will be back in a couple of weeks at least.
Elena is also not in action because her artificial arms may attract attention in the Depression. Simmons comes up with more realistic arms, which Elena is reluctant to use. She eventually gets used to them, because they also include touch. The Shrike parts inside of her have also been broken down, so she’s fine.
As for Agent May, she’s in a healing coffin after her fight with Izel last summer. She’s being repaired in a special tube, and is expected to recover.

While walking in 1931 New York, the agents also discuss how they have to navigate the past, and not do anything that may affect the future. That means Deke can’t file patents or ask for Zimas.

It’s not long before they clash with the Chronicops, especially when they figure out there is no way they’re Mounties (that’s what LMD Phil claimed). They manage to bring back one, while stealing a truck.
Meanwhile, thanks to a bottle of illegal booze, Mack and his crew head to a speakeasy which would soon become an SSR safe house. They’re surprised by who runs it…

It’s hard to picture Patton Oswalt as a bootlegger, but then again not all of them were Jimmy Cagney. As Ernest Koenig (probably the grandfather of the current clan), Patton does a fair job as a tough guy, but he needed a bushier mustache.
Anyway, Koenig has an assistant named Freddy (Darren Barnet) who recently lost his dad. The agents think the Chrons are targeting then Governor Roosevelt, because he would later create the SSR.
However, Simmons and Enoch (Joel Stoffer) gives the Chron a malware overdose, and they learn the target is really Freddy.

After FDR has his semi-illegal party, Mack and LMD Coulson are told about Freddy. It’s revealed a girl gives him some vials that she calls “the future”, just as the Chrons try to kill him.
The agents also learn Freddy’s dad is Wilfred Malick, and his future son Gideon would create the American branch of HYDRA. The Chrons think if there’s no HYDRA, there’s no SHIELD.
Actually, that’s kind of short-sided. If it wasn’t Malick, it would have been someone else. For this plot, though, SHIELD has to save HYDRA to exist.
What good are good guys without villains?
Very clever, Chromicons, although they know if that doesn’t work, they have lots of other targets to hit.

Finally, Enoch learns May has escaped from her healing pod. He doesn’t notice she’s on the ceiling, with an expression that would make Sadako from The Ring shudder.

It’s a good start to what hopefully is not the final mission, but the last one before they might return on Disney+ or a major movie (and why not?).
At least we’re promised the return of Daniel Souza, but how about Grant Ward coming back, or Lance and Bobbie? Heck, the agents could find Dottie from Agent Carter, who thinks they’re aliens sent to destroy the Earth…or at least the American belief that women should just smile and make meat loaf for their men.

Hopefully the time travel doesn’t cover the entire season. There has to be twist where the Chrons “win”, but SHIELD has one last chance to undo it.
Then there’s one last battle, most likely with the Kree. Maybe they’ve been “reassigning” the Chroms, and if so, that would set up one heck of an Endgame. We shall see.