That's exactly what it's all about. Tachankas were extensively used by the Red cavalry from 1920 up to the 1940's. These cavalries were in fact fighting as dragoon (cavalry charge are memories from the US civil war) but the main advantage of cavalry remain it's hability to conduct hit and fade tactics and to strike deep behind ennemy lines with little need for support. The weapon on the Tachanka is not directed toward the front, it is directed to the back. (Sorry I have tried to put pictures but it seems i can't do it for know, If someone can,please feel free, Kato we need you back, Heeellppp !!!!
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A cavalry unit of the time was about a third/quarter of an infantry division but it was designed to cover 70 miles a day if needed. In addition, the Soviets had very little means of support for these units much as it would be the case in T2K. As a result, most of the force was dedicated to combat with a single support company which mission was to provide everything necessary to feed and supply the unit.
In addition, the Soviets had no fuel and an insuficient number of armored car. Tachankas were then filling this role. The carriage was brought in support position before action and, then, provided heavier fire support to the troops. It still had the hability to get away as soon as the action was over and it had the hability to remain with the fighting force, as I said covering the retreat. Light artillery (and the like) were used in case of large scale actions, Tachankas were used for more limited but particularly anoying guerilla-like actions. And they proved highly efficient tools as they contributed to the defeat of the entire world. They were used with success against white russians, english, french, germans, americans, japanese, czech and poles. They were highly instrumental in bringing victory to the soviets. However, they proved highly ineffective if used for regular actions. There is no doubts about their efficiency as there are plenty of offical reports on them through military archives (Russian, French, British...). In the way it was fighting, the red cavalry was indeed fighting on foot, but it was getting as close as possible to its objective and horses were not left that far behind. Basically, they were rushed to the field, they were getting off horses and fighting on foot. Finally, they were quickly getting back on their horses before infantry reinforcements could arrive. It was a very risky tactic but it proved highly effective against hill prepared, understrength and carefully chosen objectives. Extensive recon before action was more than important and was conducted carefully (In a division, a full company was only dedicated to recon missions). Then, they had designed specific instruction/tactics to use these Tachankas (sorry I have no time to translate you the official instructions that I have stored in my own archives. I should go through at least 3 boxes of paper and 1500-2500 pages of archives to find about 60 pages and drawings on how to use them: official instructions from the soviet army in the 1920's). I'll do that sometimes but not now.
I know that plenty among us think of cavalry in T2K as being very unlikely but I don't share this view. Of course, you would not have cavalries numbering 10.000 horses but smaller units (100-2000 horses) should be around and not only among Russians. Actually, US might be more capable of building such units (and Americans are no more stupid than Russians). They would not be used to conduct large offensive but they would be effective recon units and perfect tool to put a mess within supply lines. In addition, in many area cavalry will be the only units that you could dispatch fast enough to support sensitive sectors.
Of course, civilians will start eating horses but what military leadership (even local) that remain will quickly put an end to this under the threat of death penalty (except if the commanding officer is a fool and an idiot). If I was a local commander in T2K I would rather kill civilians trying to eat horses, feed them to pigs and eat the pigs. It's even ecologically responsible and healthy (no risk with prion).
In fact, without cavalry, the Twilight War is simply over (IMO). You still have vehicles and armor but you lack the fuel for any significant action (not to talk of ammo and spare parts). Without horses, you are stuck were you are. Krakow OOB is a perfect exemple of what regular T2K OOB should be. You have a few tanks for emergency, most of them being pillboxes. You have a heavily defended perimeter forming a good stronghold. You have a few lighter armor for sensitive escorts. Most of the recon and daily supply work is conducted with horses (mules, donkeys, oxes...), however. You need horses to fill the gap and retain some mobility.