Unless they were to go full Days of Future Past and literally wipe everything after TF2007 out of existence, it would be nigh impossible to after TLK. Forget a new director who would understand the characters better, the continuity is too screwed up and filled with holes to fix, which is why it was easier to straight up reboot with Bumblebee.
Despite being a mess of a movie, continuity wise, ROTF doesn't create too many headaches. Saying Megatron works for this guy named the Fallen, while annoying to many, is an easy retcon, and having the seekers on Earth prior to everything that went down isn't too big of an ask either. DOTM, while a better film overall, is where things get a little trickier. Megatron says that he and Sentinel were going to rendezvous on Earth to (presumably) retrieve the All Spark and use it to rebuild Cybertron. But was this a decision Megs made on his own, or by the Fallen's decree? And they knew of the Matrix, how? Did the Fallen tell them about it? Did Sentinel know the Fallen?
This is really the biggest problem of the first three, or the Witwicky Trilogy. Because with the mass legion of Decepticons being hidden on the moon begs the question, why didn't they fly down in 2007 or 2009 and help out? Imagine the battle in Mission City, the Autobots are winning, and Megatron calls in the moon troops. Autobots get creamed because surprise attack, Earth is dead, Decepticons win.
Age of Extinction then raises interesting questions that aren't answered, leaving open plot threads for a fantastic sequel we never got. 'The Creators' Lockdown mentions. Who are they? Are they the Quintessons? Who are the knights that Optimus was supposedly a part of? These are questions that add to the world instead of making it more confusing. Then we get The Last Knight, and the answers make things more confusing. I can honestly buy the King Arthur stuff, that's an interesting twist with Merlin being a charlatan. The rest of it? Nope.
This takes the realistic idea of the Seekers being on Earth in the early to mid 1900s and blows it up to prosperous levels. Because I guess ancient Autobots helped Harriet Tubman and the underground railroad and Ironhide fought in the American Revolutionary War? I don't have much of a problem with Bee in WWII, but the plot threads left over from AoE is what really bugs me. Apparently, Lockdown wasn't hired by 'The Creators' but by 'The Creator' even though he mentions multiples every chance he gets, unless he's just really bad at grammar. And while he claimed to have captured all the Knights, he didn't because what about those that were guarding Merlin's staff? The Dinobots can't be a part of that same group because they aren't necessary for forming Dragonstorm, so where do they fit in? Also, Prime can't be one of the Knights Lockdown wanted to capture, because Quintessa had to tell him about the Knights of Iacon like it were a bedtime story.
Also, when did they betray Quintessa and leave? When they're talking with Merlin in the Dark Ages, they mentioned their world was destroyed, so the Autobot and Decepticon war had been going on for some time. What did Quintessa even do to make them betray her? They just say she's the "great deceiver". Um, ok.
It's honestly embarrassing to scroll waaaay up and see my 2017 self try and defend the film. Granted, there are things I still like about it, but any cool ideas put forth by AoE for where the next film could go were squandered in TLK. Lockdown's motivations don't make sense in retrospect now, the Knights as a group seems confusing because Dinobots, who were those guys at the beginning with the fleshy hand(s)? Where did the Seed go? Did Optimus chuck it into the Sun to get rid of it? By providing answers, TLK actually raises more questions and breaks what little sense of continuity the films had that were already being held together by patchwork theories from the fans and floated between sensical and bad fanfiction.
I don't see how just making a couple good movies could fix that mess of a continuity unless they were to be wiped completely, and then we'd be in a similar situation with the X-Men.