Interesting. The Kabel-X process is shown in the video below:
Pump solvent under pressure to dissolve adhesive/dielectric insulation between core conductor and outside jacket on coax cable.
Pull core out of existing coax
Attach new fiber to end ofcore, which is used like a pull string to run fiber inside old coax jacket.
This 'technique' seems limited to outside-plant runs using large gauge coax, ie LMR/EMR (~0.6-1.0" OD), where a typical CCTV system is run mostly indoors using small gauge coax, ie RG-59 (~0.24-0.27" OD) .
I wonder how they deal with the incompatibilities with allowable bend radii? Coax can be bent or looped more sharply than glass fiber. Also, coax sheaths are not rigid like the animation above shows: collapsing buried cable jacket seems risky to split open and be susceptible to damage later on.
Also, at least in my part of the globe, rodents shred cable insulation like candy. Finding the breaks or damage and digging them out for repair would seem like a big cost.
A 'standard alternative' to using Kabel-X is using directional boring equipment. That approach is pretty standard where surface disruption is a concern. (see: Cable Trenching for Surveillance for more detail)