It is a general consensus that the thermite grenades aren't that good as they are tricky to use and don't deal significant/consistent damage. So here's some ideas I think should maybe be implemented:
Show a projected thermite line while the grenade is held.
Essentially just show the area off effect that the grenade would have if you threw it.
If you can see exactly how the line will be placed you can more effectively use this very precise grenade to it's full effect, blocking routes and damaging enemies more consistently.
I don't think this AoE hologram is necessary on the other "grenades" as they require less precision.
Thermite puddles/an extra AoE effect.
In Titanfall 2 Scorch's Thermite launcher would spawn small lumps of thermite on impact, either sticking to targets or becoming damaging puddles that lasted a few seconds. This effect could be applied to the thermite grenades in addition to the thermite wall.
It would be slightly inconsistent in it's distribution, however it would effectively provide a slight AoE beyond just the basic line. A further potential development could also be that when the full thermite line can't be deployed (hitting walls, landing on roof edges etc) the grenade instead spawn's extra lumps to provide the same "bang for your buck".
Let us carry more thermite grenades per stack.
Pretty self explanatory, if they are going to be worse you should be able to carry more of them. While grenade and Arc star spam is a fairly common occurrence I have yet to see the battlefield being stuffed with lines of thermite. You would still have to find 3 individual grenade as well as throw 3 individual grenades, making carrying a stack a longer term strategic choice with some slight drawbacks.
Tl:dr Let us preview the thermite line, add an extra AoE effect and let us carry more thermite grenades.
Buffing termites are just a fun way to mix up the Meta of the game and I hope Respawn is already thinking of buffing them.
After having one too many "give up Anakin I have the high ground" (aka the enemy is on a rooftop/high ground) moments I came up with a "grenade" that could offer a small counter to them.
An airburst, micro Cluster missile ( from Titanfall) that is manually detonated by the user mid flight or detonates on impact. The idea is that it is meant to help clear rooftops and provide area denial.
The main quirk is that it doesn't have an arc but instead it travel like a rocket straight forward. Damage should be low with a large Area of effect lasting a few seconds.
Due to the multi purpose nature of this equipment it might be advised to make each stack only have one missile/"grenade" for balance and to make it stand out. Since we only have 3 "grenades" we could use another one and this could be a interesting addition.
Thanks for reading my random thoughts and I hope this caused a healthy/constructive discussion.