I'd also like to see Spike lose his gluttonous habit. He nearly gets them killed many times throughout the franchise for his eating at bad times. He does with the log in V and also starts eating their hideout later in V.)
He almost eats Ducky by mistake at one point while eating. He's gonna get REALLY fat if he doesn't stop this habit. Eventually, it''ll go to his thigh.
Near the top of my list is to have Littlefoot teach those in the Mysterious Beyond to end their herd segregation and make the dino world a better place. That segregation thing is such a huge problem for the dino world and has led many to die over it.
Also, I want more leaf eater villains. After falling in love with Chomper, I feel that Sharpteeth are being dumped on too much just cause of their dietary habits.
Also, if you're gonna bring in more Sharptooth villains, why not have more friendly Shaprtooth children, but, this time, have parents less kind than Chomper's parents who won't be persuaded to be nice and will try and eat Littlefoot & co, or may even resent them for being different.
Or, have a Sharptooth that was a trickster, but somehow spoke leaf eater, be overheard by Littlefoot and the gang, but have the Sharptooth want to axe them, not mainly for food, but so they don't talk.
I'd also like to see Chomper's "Teach Sharpteeth to be nice" idea pay off one day. We say it in "The Lonely Dinosaur" but it failed miserably.
Have Chomper, perhaps older, fall in love with another Sharptooth, one who might, for a good while, not be so fond of Littlefoot & Co. Show Chomper feeling mixed emotions.
Have Ruby show up in a film. I really want that. Ruby Rocks! I want to give her a hug!
Littlefoot win against Cera in one of their fights. (Cera always seems to win in the end, even if Littlefoot gets a jab in at her.)
(Chomper eat Rhett. Just kidding.

)
Have the gang be taught to fight back against Sharpteeth when chased into a corner rather than cowering with their eyes closed and waiting to die, as they did in II and V. (If they don't handle that, they're gonna make lousy parents someday when they get older.) Look, even if Chomper was going to kill them, they could have tried and charged him. Or done the classic "Hey look, it's the Lone Dinosaur!" distraction.)
Listen, even Ozzy and Strut's "Let's jump" idea seems better, if that had been the real thing, than what the Gang of Five did.
Also, considering that they'd rather "roll like a rock right into the sea, fall right out a tree, or sink in the mud than be eaten, they'd have tried SOMETHING in V to get away or at least make the "evil Sharptooth's" job harder at getting them.
Heck, in V they coulda ran different directions to at least ensure that most, if not all, of them got away, but they foolishly ran together.
Petrie could have saved himself when they were trapped but instead, he just grabbed onto either Littlefoot and Cera and cowered like the rest. (Also, Ducky can't weigh too much more than she did in IV, when Petrie could still carry her, so he coulda grabbed her too.)
It's not like they can't try, as Littlefoot tried to hide from Dil in a crevice, which at least was SOME effort, as it made it harder to get a him, and, had he cowered like he did in II and V, he would have been Dil's dinner before the others could have broken through the rocks.)