There is no sense that a single-squad upgrade will be permanently applied in situations where future changes in the aspects of the play can occur due to games or updates.
And since beginners don’t know what gameplay looks like, developers should keep this in mind because they’re more likely to choose the wrong upgrade for their choices.
In addition to choosing a single upgrade, players need to be able to re-select the upgrade by spending extra pay (gold, points etc)
It could either have a cooldown between re-speccing or having to grind experience on that squad to change it, but having to make an entirely new account and level up all over again to change your squad talents seems like a way too harsh punishment for making a decision you later regret.
This feature would also be useful for customizing a unit based on how you want to use them in the coming battle. If I want to use my sniper squad as an artillery squad one battle, then switch them to a forward spawn point with an engineer for the next few battles. This would make gameplay more versatile, and really open up new battle possibilities, and doesn’t lock the everyone into only one playstyle.