Hmm, I believe Musketman represents this type of guys -
https://en.wikipedia.org/wiki/Musketeer and they were used without pikes very often.
EDIT: Actually, there's a big gap between general pike abandon (17th century) and muskets abandon (19th century).
IMHO, Pike and Shot deserve their separate place in the game.
While the wiki article is very good at including the non-European 'musket' armed units, it is not entirely accurate. Starting in the second sentence, for example, that muskets represented the majority of armies - that was only slightly true and only in the last 20 years of the use of the matchlock musket. The earlier Spanish Tercio, for example, never had more than about 1/3 handguns of any kind versus 2/3 pikes or (earlier) 'sword and buckler men'.
When muskets were sent off on their own in Europe, they were referred to as "Commanded Men' - because nobody not suicidal would volunteer for such a duty. Their other title by the time of the English Civil War was even more explicit: they were called "Forlorn Hopes" - representing a pretty definitive indication of their chance of surviving without the protection of pikes or Walls!
Even at the very end of the period - 1690 to 1705, pikes still represented 20 - 25% of a battalion-sized infantry unit, at least on paper. "At least on paper" is significant, because increasingly, the troops on the ground were throwing away the pikes as fast as they could because, as one officer put it:
"Any man who kills a Pikeman should be regarded as a Murderer, because he killed a poor defenseless fellow who would hurt no one not stupid enough to run upon his pike." Basically, the early flintlocks provided enough firepower that pikemen became just targets, and were quickly dispensed with.
General Pike Abandon took place between 1695 for sure, when the French noticed the battlefield at Neerwinden covered with discarded pikes because their own men had thrown them away to pick up discarded enemy muskets, and 1702, when the War of the Spanish Succession started and virtually all the French, British, Dutch, Danish, Prussian, and other German armies were firearm-only infantry: pikes were still only in general use by the Swedes, who had a peculiar tactical system, and the Spanish and Russian armies, who were simply backward. (Not my opinion only, but that of their contemporaries!)
...Specifically since 1UPT, each unit has come to represent more soldiers as there are less units; so at least on land we're talking divisions and armies rather than the companies or batteries (yes ignore the combined units that are called armies etc in game); the only definite exception being scouts. But even they don't die immediately when attacked by another unit...so logically there's not just 100 men there

Of course divisions and armies are made up of a mix of different units. You don't have a whole division of archers. They're a smaller group like a battalion attached to an army. So it's already unreal in that sense.
So I'm fine with some of the details that are being talked about being added.
The units in Civ, to make any sense, have to represent a number of men that increases as you progress through the Eras. The average City State in Sumer from what little evidence we have seems to have provided an average of 600 - 2000 men. A single Infantry Regiment in World War Two was 2500 - 3500 men, and it was only one component of a Division, which was the basic 'strength counter' of an Army, and each Civ produced multiple Armies. Part of the problem comes from sloppy nomenclature: on the one hand, Civ refers to Slingers and Archers, which are individual troop types, on the other hand it refers to a Legion, which is a Unit of 1000 - 5000 men depending on which year of the Roman Empire or Republic you are trying to represent.
Basically, Ancient Units in the earliest states (Egypt, Sumer, Greece, Babylon) for which we have any written evidence, seem to have been raised in units of 50 - 400 men, with little or no evidence for any Permanent organization larger than that other than organizational titles that simply mean "Host" or "Everybody we could put onto the battlefield at one time". That means the only semi-historical Ancient Era unit you've got is the equivalent of a Industrial Era or later Company.
So, personally, I assume that my Ancient Era units represent a few hundred men each, Classical units are about a 1000 men each (decimal organization is found almost everywhere), Medieval units about the same, Renaissance units a Tercio or Brigade of 2 - 3000 men, Industrial units a Division of 6 - 10,000 men, becoming a Modern Era division of 12 - 20,000 men and an Atomic/Information Era Brigade of 6 - 8000 men. The units of the last 25 years or so have for the first time historically, gotten smaller in manpower, but 'compensate' by being much, much more complex and expensive in equipment and weapons and firepower and mobility.
The exact size of a unit is, frankly, not important, compared to the relative Capabilities of the unit in mobility, combat power, and sustainability. Since in the game that is all relative to other units, it should be based on historical weaponry and capabilities, but does not have to be based on the exact numbers of men carrying exact numbers of specific weapons in a given historical unit.
In other words, the game does not require you to build the US Army's "1st 'Iron" Division of I Corps" of the Civil War, or the French WWI "11th 'Iron' Division", or the Soviet WWII "24th 'Iron' Rifle Division" specifically, but you can always name an infantry unit 'The Iron Division' in any Civ you're playing!