That had reminded me a fairly crazy idea I had. Probably way too crazy to consider, but I'll throw it out there.
Just as the Tercio merges the anti-mounted and main infantry lines....the fusilier merges the Recon and Infantry lines. Or you could even do it as early as Tercio if you really wanted to.
1) Remove the Zeppelin (its a very weird unit as is). Explorers upgrade to fusiliers.
2) Fusiliers and beyond get Trailblazer I and Survivalist I (giving them access to the recon trees). CS adjustments would likely be needed.
3) Starting at Flight, gun melee can take the paradrop promotion.
4) At nanotech, gun melee can take the xcom drop promotion.
5) Paratroopers, Special Forces, and Xcom squad are removed from the game.
6) (Optional) At the tech that special forces come out, gun melee all gain amphibious as an automatic promotion.
So you don't focus on making Infantry stronger, but more versatile. When it comes to pure power, ranged and mounted units are still better. But now infantry give you solid numbers and a wider variety of mobile options.