My class and role solution

Personally i don't think that there is a need for 5 classes on its own, as the overall common term for most vehicle's is AFV anyway and within the current "style" which we have there is really not a need to separate more than actually needed.

As you might see, i reduced it to the 3 basic classes which are divided in several roles themselves. In the current game there are already some roles, mainly in the AFV area, naming the Recon bonus or the Troop compartment bonus for IFV's .
My reasoning to put the LT and TD vehicles into the AFV class is fairly simple. Both current classes rely on mobility combined with a higher camo rating than MBT's and SPG's as well as having a high caliber weapon system for the most part. Overall you play LT's and TD's somewhat the same. The main difference between those 2 classes and AFV's is the view range and the camo mechanics .


1) MBT


I divided the MBT's in 2 roles to fit. One will be the heavy armored one and the other is the light armored role. By thinking of that , i tried to divide it by the actual weight, but that won't make a big difference as western MBT's tend to be heavier , even for light armored MBT's.

• Heavy armored role bonus -  HP Bonus | Higher Crew Resilience
• Light armored role bonus - Penetration and damage bonus vs same class | (less bloom when traversing compared to the same class)

These role bonuses are just a suggestion on what you can do, while i think that the heavy armored bonus is quite nice as a role bonus inside of the class. The Light armored role bonus should make it, that those MBT's are better at snap shooting when they face heavy armored MBT's . It should be mentioned that this needs a balancing, so heavy armored MBT's don't lose too much  for having armor .
However this more likely focused on early cold war / past 2nd WW MBT's , such as the Leopard 1 for example or later on the TAM, which would fit perfectly the light armored role .


2) AFV


IFV are correct ingame and their current role bonus is okay for what they do . I have some ideas for improvement, but those are not necessary at the moment, which is the same for Recon's as well. The main reason is the High Caliber role.
Overall i would give them a steady camo, like the current AFV's have, while  this one ain't that high , but it is steady and doesn't increase while standing still as it is at the moment if iam not mistaken .

LT's

• medium camo rating
• ECU should increase the max speed for the time and the "boost" should be noticeable like it is on the Exp. Tank
• If ECU is not used, you have a higher hull traverse and turret traverse ... maybe ?! (active the boost and passive the agility for the ECU aka NOS setup)
• vision range should be higher than MBT's , but lower than IFV's and Recons
• add higher shell velocity speeds (1400ms+)  as a role bonus

TD's

• medium to slightly better camo rating
• instead of damage while fully aimed, it should reduce the normalisation and increase the accuracy
• when spotted you gain increased acceleration for 2 seconds ... maybe ?!
• vision range should be higher than MBT's , but lower than IFV's and Recons

 LT's and TD's play similar at least that is my opinion and playstyle with them and i doubt that they will remove those classes as it is too common sadly that people want those and obviously to have 5 classes to show.
As for LT's iam looking forward to give them a better ECU as at the moment it is not noticeable for most LT's and a better ability to be a "quickscoper" with the option to flank better. You might as well want them to have a higher HP pool or better traverse speeds as well.

TD's is a "class" which i personally don't think is the right name for it. Most people consider something different with that name , while in the current setting, there are no Tankdestroyers anymore, though the vehicle's that have a high caliber gun are most likely to be in a support role with the option to engage in emergency a enemy MBT .
I would increase the ability to be a effective sniper, while you rely on your precision and not the overall damage.


3) SPG


The main reason why i would have a difference in here, is the different agility with a wheeled or tracked SPG system. I was thinking of adding the Mortars as an extra role, but those are tracked or wheeled as well, so it might fit it better with just having that difference .

Wheeled

• Increased gun arcs for the "turret" / "weapon system"
• higher recoil feedback after the shot (bigger bloom)
• better mobility
• worse rate of fire / maybe slower shell speed as well

Tracked

•  no 3 shot magazine loader, but single loader ! :^)

Though iam not sure what to add here, but i'am sure that Obsidian will make enough mistakes in future to jump on the SPG bandwagon. That to be said from what they said in their Q&A i already had a facepalm when i saw future "high tier" SPG choices ....


Conclusion

I think that reducing the classes to 3 and adding one or more roles to the classes itself will be the way to go . This should add a identity to most vehicles that are in game or in the future, as it can be easier to add a role than trying to fit a vehicle into a class itself . However some PJSalt will come tomorrow with a "problem" that bugs me quite often :(