It is true that many tech skills today are extremely specialized. These skills mainly involve connecting two systems to one another and don't utilize an overall view of the system. These types of specialist may be in trouble in a post collapse society. You need to have an overall view of the systems and how things connect together.

There are many tech skills that will be of importance in a post collapse society: electricians, auto mechanics and mechanics in general, civil engineers, process engineers, computer programmers, chemical engineers, organic chemists, small engine and appliance repairers, heavy equipment operators, and Ham Radio operators. For example, someone who is versed in rely logic can create an automated process without complicated computer programming.

Process engineers know PLC Programming which is a digital computer used for automation of typically industrial electro-mechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures. PLCs are used in many machines, in many industries. This knowledge would allow individuals versed in PLC to read prints of many different types of machinery or computer systems. 

Computer programming knowledge allows for machine interface for extreme automation. They can gain access to high security areas. They can operate in DOS based and Linux systems. With items like a raspberry pie,  a low cost, credit-card sized computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse, and an arduino, an open-source electronic prototyping platform allowing creation of interactive electronic objects, these individuals could create an automated trip switch with an alarm. They would not need a computer to do the job, the arduino would trigger the alarm. Ken suggests that individuals with this knowledge start stocking up on these parts now so they can bring value to groups in the future.

Chemical engineers and organic chemists can do much more than applying their skills for chemical warfare. They can do chemical tests on soil and water. They can find rare earth materials needed for batteries and gun powder. They can find Ferris materials, materials with iron, and mix them in such a way that they can help generators produce more power. They can actively take on tasks like creating wood gas engines for vehicles while you are out completing other tasks that your skill sets are more suited to.

On a personal preparedness level you should know a few things. You should be familiar with Ham Radios. You can own and listen to the radio legally but you can't speak unless you are certified to do so. The only exception is in an emergency situation, for example a tornado, natural disaster or civil unrest event. It is not hard to get your license but if you are going to start programming it you will need a mentor. A Ham radio is programed to connect different frequencies to your radio so you can listen and speak over many different channels. You should also have an understanding of basic electrical wiring. Also, you should have an understanding of the Linux system and Windows DOS commands. You should learn "ping" because it allows you to access remote systems. The final personal preparedness item is you should learn "TrueCrypt." This system allows you to encrypt a hard drive device so you would be the only one who could access your drive. Also you should learn "Ubuntu" because it allows you to further encrypt your files and increase your security.