New companies (beyond AI.xml ones) spawning?

[JC_Denton]

I've noticed a few times that later in the game, companies that aren't in the AI.xml file can spawn.  This seems to be to keep the number of companies at or above a certain level - 23 or so?

However, I've also seen this not happen, so I'm curious, what are the conditions for this to happen/is it based on one of the game setup options?  Ideally I'd like to tweak it to make it easier for the Big Three and AMC to dominate the market without AI.xml-less competitors, only a few intrepid souls such as John DeLorean dreaming of disrupting the industry.

[Eric.B]

The game will prevent a complete death of the game world by generating new companies once a percentage of companies have bankrupted.

A solution would be to have companies become marques, but in all likelihood I probably need to make this a starting game option.