The Black Panther suit is almost just as important as the mantle itself, which was evidenced when the character debuted in Captain America: Civil War and in Black Panther. There are a lot of comic book features that fans could see in the next version of the suit, especially since another character will likely be wearing it going forward.
Black Panther 2 is set to come out in 2022, and with the release of the film, many are expecting to see the debut of a new suit as well. While T'Challa's current suit which he received in the first movie has served him through both Avengers: Infinity War and Avengers: Endgame, it is due for an upgrade, no matter who ends up wearing it.
Hard-Light Shielding
In, the comics, while the Black Panther's habit is made up of a Vibranium-mesh weave which renders his suit bulletproof, the suit can also create a shield made up of hard light to provide T'Challa and his companions with an extra layer of defense.
This would be a great feature to add to the suit, it would have been incredibly useful in protecting Agent Ross from being shot.
Invisibility
Another major ability of the Black Panther is stealth. A great example of this is in the opening fight scene where he comes to get Nakia while she is operating undercover and he uses the darkness to his advantage to take his opponents by surprise.
However, that is one of the film's only fight scenes to take place at night, and since most occur during the day, its much more difficult for him to hide in the shadows. An upgrade could allow the suit to allow him to render himself completely invisible, truly making him a threat that his opponents wouldn't see coming.
Teleportation
One of the advantages that the heart shaped-herb provides is that it grants superhuman speed to those who take it. That speed is perfectly demonstrated in Infinity War when T'Challa is shown to be slightly faster than Captain America. However, there are some cases when being quick isn't enough, which is why the next Black Panther suit should add the ability of short-range teleportation.
Even if the range of the teleportation is small, it would still be a great upgrade to have and would allow the Black Panther to keep up with opponents that are faster than them. It would have been perfect for when he was chasing the Winter Soldier in Civil War.
Energy Daggers
Black Panther's main weapons are his Vibrainum claws which can easily slice through the majority of materials. While they are worked great in past movies where most of the fights relied on martial artists and took place in close contact, his classic energy dagger from the comics would be a great addition.
The daggers come in the form of two blades made of energy that T'Challa can use as knives or as darts to throw at enemies, making the wearer just as effective of a fighter from long range.
Holograms
There are quite a lot of functional holograms in the world of Wakanda. They are used for video chats from Kimoyo beads, and the characters can even interact with them, like when Shuri and Ross use them to take control of other vehicles from a distance.
In the comics, advanced holographic technology is available in the Black Panther suit. One of the primary functions being the ability to create holographic duplicates of themselves to distract or confuse opponents. Not only does it create duplicates of the suit but it can also allow the wearer to take on the appearance of any chosen person. The suit can also disguise itself as regular clothes which would have been helpful when T'Challa was trying to blend in Tokyo while looking for Klaue.
Artificial Intelligence
If Shuri ends up receiving the mantle from her brother in the second film, one major thing fans could see her include in her version of the suit is her Artificial Intelligence, Griot. Griot was featured a little in the first film, mostly providing updates to Everett Ross on the status of his aircraft. Although Griot is usually only used in her lab, it would make perfect sense if she was able to utilize it while she operates as the Black Panther.
While one could argue that it would make her too much like Tony Stark, that comparison could actually be a good thing. The use of an AI could provide a character for her to talk to like how T'Challa would communicate with her in the first film, she could even update it to have T'Challa be the new voice of the AI.
Wings
In the comics, Shuri has the ability to transform herself into a flock of birds. While it's unlikely that she will have that ability in the MCU, she could end up making one of her best inventions from the comics, a pair of wings made of nanotechnology which she keeps in a necklace and can wear along with the Black Panther suit.
Adding wings to the suit would do a great job of differentiating her from her brother and solidify her as a unique Black Panther.
Delivery System
The main upgrade T'Challa's suit received between Captain America: Civil War and Black Panther was the addition of nanotechnology which allowed the Black Panther suit to be stored in a necklace that he can summon with his mind.
As Iron Man showed with his Mark 50 suit, there are many uses for nanotechnology. One that could be incorporated into the next version of the Black Panther suit is the ability to transform the gloves into a delivery system by allowing the fingertips to fashion themselves into needles that can be used to administer cures, antidotes, or even poisons.
Energized Gauntlets
In Black Panther, Shuri made it so that the new suit collected and redistributed the energy used on it. While it worked well in the film, an upgrade should use the built-up kinetic energy and send it to his claw which can burn opponents rather than simply hitting them with a blast of kinetic force.
In Infinity War, fans saw how easy it was for Thanos to deflect T'Challa's punch and then use it against him, so this is a feature that would be perfect for situations like that when serious damage is required and when stunning the opponent isn't enough.
Arms Jammer
Oftentimes, T'Challa would find himself facing off against men using some serious firepower, and while most aren't able to do damage to him, some can still be an inconvenience.
It would be interesting to add technology in the suit's utility belt that can emit a wave that could cause all nearby weapons to backfire, rendering them useless in a fight and giving the wearer an additional advantage. Something like this could have been extremely useful in the scene where he and Okoye go and rescue Nakia, since all of the men were armed.