People have suggested in the past that they should get a Jaeger Light Infantry Recon G43 DMR which would change their role a bit, but I'm not sure how good that would be paired with 3 Assault Rifles. It might be too strong because it can snipe models that were chipped away by the assault rifles, or it might be too weak because the assault rifles don't deal enough damage at long range and eliminate models faster than the marksman's rifle at close range.
Maybe replace the current grenadier one with the PGren one and give the DMR G43 (only one) to grenadiers themselves at 60 Munitions. So we have,
3 G43 Rifles Pgrens with additional 10% RA for their loss in close range DPS. Basically upgrade makes your PGs more durable in return for the lost close range DPS.
And,
1 G43 DMR Grenadiers, basically locking out the LMG42 and makes them a support squad rather than a standalone squad. Just like JLI but with a later timing. (Maybe even reduce the Gren G43 Snipe treshold to 60% between JLI 75 and Pathfinder 50).
EDIT : I feel like I'm gonna receive a lot of hate for this suggestion.
It may be a bad idea to have the Jeager Light Infantry upgrade grant 2 different types of G43's to 2 different units, which would exacerbate the confusion surrounding the different G43's and their roles.
And maybe this achieves to actually make sense having the same looking upgrade on different squads but still reinforcing each of their roles as close range assault squad and long range support infantry.